From spotless sun to warped spacetime

A solar flare observed in Dec. 2006 by NOAA's GOES-13 satellite. Credit: NASA

The sun is at the bottom of the roller coaster with nowhere to go but up. NASA released a revised forecast this week on when the sun is expected to bounce back from its quiet spell. Solar activity like flares and sunspots wax and wane in an 11-year cycle. Among the more visible effects of high activity are increased sightings of the aurora borealis. We were supposed to bottom out on the cycle's low end in March of 2008 with a new maximum in 2011 or 2012. The reality is we're in the deepest valley of solar quietude in a century. Sunspot counts are extremely low and there've been no significant flares for more than two years.

Science is all about revision and modification based upon new information from the biggest source of all -- Mother Nature. According to the latest solar forecast, the sun should remain generally calm over the next year and then start to rumble to life again. The new maximum of Solar Cycle 24 is predicted for May 2013 but with the fewest number of sunspots visible per day since 1928. Already there have been some uptick in activity with the appearance of a trickle of new spots and an increase the amount of energy the sun gives off in the radio end of the spectrum.


Yearly-averaged sunspot numbers from 1610 to 2008. Researchers believe upcoming Solar Cycle 24 will be similar to the cycle that peaked in 1928, marked by a red arrow. Credit: NASA/MSFC

Scientists make predictions based on current trends but don't know for certain what route the sun might take. Will we experience a new Maunder Minimum -- a 70-year-long period in the 17th century when the sun was spotless? Dean Pesnell of the Goddard Space Flight Center put it best: "Go ahead and mark your calendar for May 2013," says Pesnell. "But use a pencil."

This past week saw the 90th anniversary of the first empirical test of Einstein's Theory of Relativity. That's a fancy way of saying that scientists found proof in the real world of Einstein's prediction that gravity bends light. According to the theory, objects like the sun are massive enough to literally curve local space and time -- spacetime for short -- around themselves, creating a kind of pocket or dimple in its fabric.

To help you visualize curved spacetime, imagine a child standing on a trampoline. The child's weight changes the depth and curve of the dimple beneath their feet. A heavier child makes a deeper dimple. Substitute the sun for the child, and space for the trampoline surface and you begin to get the idea of how gravity affects space.

For an excellent, graphical illustration of spacetime, be sure to check out this short video:



Einstein predicted that light from a background star just touching the edge of the sun would be deflected upward and away from the edge by the sun's enormous gravity. Credit: Jose Wudka

So how you prove the sun really warps space? Let's say we look at a star in the same direction as the sun. Since the sun is too brilliant to see any stars near it, we'd have to wait for a total solar eclipse to do this. With the sun's light blacked out by the moon during totality, we might get lucky enough to see a star close to the sun's edge. Einstein said that the warping of space near the massive sun would cause the beam of starlight to appear to come from a slightly different direction compared to its real position in the sky.

Isaac Newton's original Theory of Gravity predicted massive objects with lots of gravity would bend light too, but his prediction of how much was only half of Einstein's. Relativity Theory predicted that a beam of starlight grazing the sun's edge would be deflected by the incredibly tiny but measurable amount of 1.75 arc seconds. That's the size of a dime seen from a distance of 1.3 miles. For comparison, the full moon is 1800 arc seconds across.

As soon as World War I ended, English astronomer Frank Dyson recruited Arthur Eddington, professor of astronomy at Cambridge, to sail to the island of Principe, off the coast of West Africa for the best view of the May 29, 1919 total solar eclipse. Eddington was charged to test Einstein's theory by photographing stars near the sun to see if they were deflected by the amount predicted. Luckily, the eclipse happened against the background of a rich and bright star cluster, the Hyades in Taurus. Chances were excellent at least of few of them would be close enough to the sun's edge to show a measurable deflection. (Einstein in 1921, left, and Arthur Eddington)


One of Eddington's photos of the totally-eclipsed sun taken on May 29, 1919. Star used to prove Einstein's prediction are shown between pairs of tick marks. Credit: Philosophical Transactions of the Royal Society of London

The total part of the eclipse lasted 400 seconds but only in the last 10 seconds did the sky clear. Eddington got an image and compared it to one taken of the same stars when the sun was not present. The result was a 1.61 arc second shift, in very close agreement with the prediction.

Media attention propelled Einstein to overnight celebrity. Since then, the Theory of Relativity has passed every test scientists have thrown at it. Despite its weird, counterintuitive predictions of warped space and time, Einstein's brainchild accurately describes many aspects of the natural world.

(Credit on Einstein portrait: Oren Jack Turner; Eddington portrait: American Institute of Physics Niels Bohr Library)

Posted by: rking@duluthnews.com on 5/31/2009 at 12:19 PM | Comments (1) | Permalink

Fuzzy thoughts on a fine day

A starry sky with a bright moon? Snowstorm in spring? No, just millions of poplar seeds flying by in the wind yesterday afternoon. Photo: Bob King

If you've ever wanted to accuse me of writing fluff, today would be the day. In northern Minnesota, we're at the peak of pollen season. Pollen reveals itself by small colorful halos around the moon or yellow dust on the hood of your car or on the surface of ponds. Some of us don't have to see it to know it's there -- our itchy eyes and constant sneezing are evidence enough. But there's more than pollen flying around these sunny days. Born by the wind, the air is filled with small bits of fluff blowing by.

Yesterday you couldn't miss them, and if you looked in the direction of the sun, taking care to shield your eyes from direct sunlight, they powdered the blue sky like stars. Hundreds of thousands, no, millions of them passed overhead. Take a look today and allow you eyes to focus into the deep distance. You'll see what I mean.

From past experience, I knew these fluffies were seeds, many if not most from the poplar trees that are common to our region. The seeds are attached to silky hairs that allow efficient dispseral by the wind.

A close up of one tufted seed. Light reflecting off and around the delicate hairs that keep the seed aloft diffracted light into iridescent colors. Photo: Bob King

After seeing about 8 million of them from afar, I wanted to track one down and see what it looked like up close. This was harder than I imagined. The silky balls were so tiny and delicate, my fingers were much too blunt an instrument to hold them individually. I finally had to gather up a small pile that had accumulated in the garage. Through the closeup lens, the tiny hairs, much thinner than thread, sparkled with vivid colors in sunlight. Evidently, the hairs are so narrow that they diffract light, causing a display of colors similar to light passing through a spider web or water droplets in clouds. Nature always proves that the closer you look, the more surprises you'll find.

I always look forward to the 5-day-old moon because of three magnificent craters that vividly illustrate layers of time in the moon's history. Last night's moon showed them splendidly. Theophilus, Cyrillus and Catharina are all about 60 miles in diameter but each has a different age that you can tell just by looking.

The trio of featured craters along the moon's terminator last night. Theophilus is 14,000 feet deep and its rim rises 3 1/2 miles above the surrounding terrain. Details: 1400mm focal length at f/14, 1/15 second exposure at ISO 100. Higher res photo. Photo: Bob King 

Theophilus has a crisp, sharp outline and distinct central mountain peak, all indications of its youth. Youth is relative on the moon -- we're talking 1-3 billion years old. Notice that Theophilus overlaps Cyrillus, indicating that the asteroid that created Theophilus, struck after Cyrillus formed. Another indicator of Cyrillus' greater age is the broken, worn-down appearance of its rim and a less distinct central peak. Being older, Cyrillus was subjected to millions more years of meteorite and asteroid bombardment than its neighbor.

Catharina is older yet. Its central peak was probably buried under lava that welled up from cracks in the crater's floor and part of its rim has been obliterated by impacts, all signs of age. Small telescope users can see the trio with their own eyes tonight. Look west of the moon's terminator, the line separating day and night.

The moon will hang between the planet Saturn and the star Regulus in Leo tonight (May 30). This map shows the sky around 10 o'clock. More advanced observers can watch for the shadow of Saturn's moon Titan to cross the planet's northern hemisphere starting at 11:34 p.m. Central time. Created with Stellarium.

Posted by: rking@duluthnews.com on 5/30/2009 at 10:02 AM | Comments (1) | Permalink

Stung by a midnight scorpion

I've been bitten by the Scorpion again. 'Round about midnight last night I got up for a walk after falling asleep on the couch in front of too much late-night comedy. All the fully leafed-out trees gave the wind a full-throated, strong voice. This is such a satisfying sound especially when you recall the thin hissing of the winter wind through bare branches.

The W of Cassiopeia is easy to see low in the northern sky during late May and early June. For much of the U.S., the constellation is circumpolar, meaning that it never sets as it circles the North Star. Details: 35mm lens at f/2.8 with diffusion filter. 25 second time exposure at ISO 1600. Photo: Bob King

To the north below the North Star was Cassiopeia the Queen, looking more like a W than at any other season. Except for southern Florida, Cassiopeia never sets for virtually all of the U.S. But the further north you live, the higher up in the sky and easier it is to see. Here in Duluth, where the North Pole is always in sight, Cassiopeia is not hard to find.


Scorpius, harbinger of summer, becomes visible again in the southeast around the midnight hour in late May. The stinger is the pair of stars at far left. Beta Scorpii is a fine double star for small telescopes. Created with Stellarium.

But it was Scorpius the Scorpion that really caught my eye. I turned the corner and found it rearing up in the southeastern sky to the left of our good friend Libra the Scales. Like Orion, Scorpius has three stars in a row but lined up vertically rather than horizontally like Orion's Belt. A few "fingers" to the left of the three is the pinkish twinkler Antares, Scorpius' brightest star. Antares is a red supergiant star with a diameter about 700 times that of the sun. Put in the sun's place, Antares would extend beyond the orbit of Mars. Goodbye inner planets! At its current distance of 600 light years, we're still safe.

Late May through June is the best time to view Antares because it rises around sunset and stays up all night. The sun is near Antares every year in late November, a time when days are short and the sun rides low in the sky . You know winter's long past when Antares leaves the sun's glare and joins the evening stars. Next week, the gibbous moon will occult or pass in front of the star during its monthly swing through the constellation. You can check here next Wednesday for details.

The Head of Scorpius, with orange-colored Antares, pokes out between the trees last night. Details: same as above. Photo: Bob King

Every scorpion has a stinger. If you look at the map, you'll see a pair of stars off to the left sitting right on the horizon -- that's Scorpius' business end. It's only half a fist high at best from Duluth and takes some effort to see. Down in Florida, the star is nearly three fists high! You get some, you lose some. We get a queen and Miamians get a stinger.

Telescope users will have fun looking at one of the prettiest double stars in the sky in Scorpius. Check out Beta, the topmost of the three stars that form the scorpion's head. There are also some marvelous globular clusters near Antares which we'll also explore as the constellation becomes better placed for viewing in June.

(Credit: Scorpion image by Tomas Castelazo)

Posted by: rking@duluthnews.com on 5/29/2009 at 10:42 AM | Comments (0) | Permalink

Foraging on the dark side of the moon

The thick crescent moon photographed through a small telescope last night around 10 o'clock. The shapely, dark oval patch at the 4 o'clock position is Mare Crisium or the Sea of Crisis. Details: 1300mm focal length at f/14, 1/15" at ISO 100. All photos: Bob King

The clouds took their time wafting away last night. First to escape their cover was the 4-day-old crescent moon, then Castor and Pollux, followed by Leo the Lion and all the rest. I had some fun taking pictures of the moon through a small 4-inch refracting telescope. The mount I use is equipped with a clock drive, a device that turns the telescope to track the stars. Once you find your target, you tighten a couple knobs on the mount and just sit back and enjoy. The clock drive locks on and prevents what you're looking at from drifting away.

We all know that the Earth rotates, and if you've been studying the sky for any length of time, you're probably aware that Earth's rotation makes the stars all move slowly westward during the night. When you look at something through a telescope at 200x, you're also magnifying the rotation rate 200 times. Believe me, after seeing Saturn sprint across the field of view without the help of a clock drive, you have a whole new appreciation for Earth's rotation.

The sunlit crescent is overexposed in this photo in order to capture the fainter portion lit by Earthlight. Details: same setup as above but with a 15-second time exposure.

In the photos, you see both the sunlit crescent and the larger, dimly lit remainder, illuminated by light reflected off the Earth. Does the Earthlit moon have a slight bluish tint? It does to my eye. Perhaps it's because our planet has far more ocean than land, giving the reflected more light a more bluish cast that overwhelms the browns, greens and white of land and clouds. If you've ever walked under a bright red tree on a sunny fall day, you may have noticed how the leaves color the light around you. The same principle might be at work with Earthshine.

In this version, I've added the names of a few craters you can see in binoculars or a small telescope. The terminator is the boundary line between lunar day and night. It looks so bumpy because the sun is just rising along that arc, highlighting crater rims and mountains against deep shadow.
 

In my 10x50 binoculars I could easily make out a few of the lunar seas, those large dark areas that form the face of the "man in the moon". Craters were more difficult but I did see Tycho. Through a small telescope you can see all the features I've labeled and many more. If the sky is clear tonight, try it yourself and see what you can find. Detail in the dark portion is easier to see if you place the bright crescent out of your field of view.

Whenever I study the Earthlit portion of the moon, I feel like some kind of nocturnal animal pawing around in the darkness looking for tasty morsels. I'll be there prowling again tonight.

Just look at those tiny gems sparkling along the moon's edge. Each is either a mountain peak or the top of a crater catching the first rays of the rising sun. The dark portion of the moon is bathed in Earthlight, which is bright enough to reveal craters like Tycho. At left, the brilliant crescent is illuminated by the sun.

My favorite sights last night were the three mountain peaks -- or more likely, crater walls -- that caught the low, glancing rays of sunlight so only their very tops were shining. They were simply beautiful and conveyed the ruggedness of the lunar landscape in a most picturesque way. By tonight, those tiny, star-like peaks will have filled out into crater rims, and if we're lucky, another one or two or three new ones will take their place further along the moon's circumference.

Posted by: rking@duluthnews.com on 5/28/2009 at 1:27 PM | Comments (3) | Permalink

How to find balance in your life

On May 22nd, Dutch amateur astronomer Quintus Oostendorp recorded a space station flare through his backyard telescope. Here's the movie he made using his Canon 1000D. The bright flash you'll see is sunlight reflecting off one of the station's solar panels.

OK, yesterday I said there was just one good pass of the space station for our region, but after seeing this video, I was inspired to let you know of one last, not-so-great-but-still-visible pass tonight (May 27). Beginning at 9:54 p.m., watch for the station to appear in the west and make a very low pass from southwest to southeast over the next few minutes. It'll only be about one outstretched fist above the horizon at best. I hope you'll catch a flare like the one Oostendorp spotted. Pretty amazing, isn't it?

The moon walks with the twins Pollux and Castor in Gemini during twilight this evening (Weds. May 27). All maps created with Stellarium.

At the very same time you're out satellite seeking, look west to the crescent moon, which will be parked near the stars Pollux (PAHL-lucks) and Castor, the two Gemini twins. The spooky, dark portion of the moon, caused by sunlight reflecting from Earth to moon and back again, will be very obvious. It's called Earthshine but also goes by the more poetic "the old moon in the new moon's arms".

As night finally takes hold around 10:30 p.m., face due south to spot the bright star Spica in Virgo, about four fists above the horizon. Spica can help you navigate to a small, dim constellation of the zodiac called Libra the Scales. Libra is the warm-up band for the big acts of Scorpius, Sagittarius and the Milky Way that follow.

The sky as you look toward the southeast around 10:30 -11 p.m. this week. Libra is a faint group about two fists above the horizon and two fists to the left (east) of Spica in Virgo.

The four stars represent both a real, physical balance and the concept of balance. Alpha and Beta Librae, which go by the delightful Arabic names of Zubenelgenubi (ZU-ben-el-je-NEW-bee - Alpha) and Zubeneschamali (ZU-ben-es-scha-Molly -- Beta) outline the balance beam. Two fainter stars below are the pans used for weighing. Remember the wobble of the Earth's axis called precession from the other day? Not only does that wobble cause our polestar to shift, but over the centures, it also shifts the sun's position along the ecliptic, that imaginary path taken by all the planets, moon and sun in their wanderings across the zodiac.

Libra represents a balance in more ways than one.

Back in Rome's heyday, Libra was part of Scorpius. The two "Zubens" are Arabic for the Scorpion's southern and northern claws, referring to the pincers of the scorpion. Approximately 2000 years ago, when Caesar was king, the sun was in Libra during the fall equinox. You'll recall that the equinox is a sort of balance point in the seasons when day and night are briefly of equal length. The Romans re-assigned the stars that were once in Scorpius to the constellation of balance, Libra the Scales.

Alpha Librae, also known as Zubenelgenubi, is a double star that you can easily see in any pair of binoculars. Credit: AAO/STScI/WikiSky

Libra has a treat in store for binoculars users ... and perhaps for the eagle-eyed as well. Alpha is a double star 77 light years from Earth and one level fainter than the Big Dipper stars. With binoculars you'll have no problem seeing the companion sitting right above it. The two take more than 200,000 years to orbit about the other. Those with acute vision will likely be able to split them with eyes alone. It's tight though! Let us know how you fair the next clear night.

One final thought. Notice how close Alpha is to the ecliptic. That means it stands a better chance than most stars of being covered by the moon, sun and planets as they travel along the ecliptic path. Astronomers call those events occultations. The next occultation of Alpha by a planet will occur on November 10, 2052 when Mercury will pass directly in front of the star. Perhaps we should call the event a planetary pinching??

Posted by: rking@duluthnews.com on 5/27/2009 at 12:52 PM | Comments (0) | Permalink

Thief on the loose

Evening visibility of the International Space Station is about to wrap up for May with just one good pass left. Watch tonight (May 26) in twilight for the ISS to rise in the northwest at 9:28 p.m., cross the southern sky and then enter Earth's shadow in the southeast at 9:33. After a short spell of invisibility, the station will resume morning passes over the U.S. in June.

The galaxy M87 is located in the "Y" of Virgo not far from the planet Saturn. This map shows the sky around 10:30 p.m. looking southwest. Created with Stellarium.

Several days ago ('May night masterpiece' blog) we visited one of the sky's brightest globular clusters, M13 in the constellation Hercules. Only about 150 of these big chandeliers of stars reside in the Milky Way galaxy. The situation is far different in a galaxy called M87, the 87th entry in a catalog of deep sky objects compiled by French astronomer Charles Messier. This enormous galaxy, nearly five times the size of our own, is about 50 million light years away and located at the center of a cluster of 2000 galaxies called the Virgo Cluster.

M87 is the large galaxy in the center of this photograph. Most of the little fuzzy dots surrounding it are some of its stash of 12,000 globular star clusters. Two smaller galaxies are seen below right. Credit: Anglo-Australian Observatory/David Malin images

According to 2006 data, this monster has upwards of 12,000 globulars, more than any other galaxy known. Just look at that photo. All those fuzzy spots centered on M87 are globular star clusters. Since many globulars contain 100,000 stars or more, that comes to over a trillion stars between them. For comparison, our entire galaxy contains only about 400 billion stars. How did M87 get such a huge share of clusters?

The galaxy M87 is at the center of the Virgo Cluster, an assembly of 2000 galaxies moving through space together. The cluster is found within and just above the "Y" outline of Virgo. Credit: Digital Sky Survey 2/Mt.Palomar

As you've gathered by now, M87 is huge, and that means it has a lot of gravitational pull in the neighborhood. Like some titanic bully, M87 has likely used its gravity to steal globular clusters from other nearby galaxies as they swarmed about the cluster's center. The more it grabbed, the bigger it got and the better able it was to snatch more. M87 just can't help itself.

I couldn't resist sharing this photo of the globular cluster Omega Centauri, the brightest one visible from Earth and the largest in our galaxy. About 10 million stars orbit the center of the cluster. It's easily visible with the naked eye but only from the southern U.S. and points south. Credit: NASA/ESA/Hubble Heritage Team

Our own Milky Way even has a connection to this globular snatcher. The Virgo Cluster has enough mass to wield its gravitational influence even out here in the hinterlands. The group of galaxies we cluster with, called the Local Group, is tugged toward Virgo, in part by the ravenous maw of M87.

Posted by: rking@duluthnews.com on 5/26/2009 at 12:22 PM | Comments (5) | Permalink

It all depends on your perspective

One of a skywatcher's secret joys is a clear sky when the weather forecast calls for certain clouds. This happened last night. Up until 11, the stars shone placidly over the neighborhood. Not long after, all the meteorologists smiled again as their prediction ultimately came true.

Take a look low in the northwestern sky during twilight tonight (Mon. May 25) to find the crescent moon. You can use the bright stars Procyon and Capella to help point you there. All maps reated with Stellarium.

The crescent moon returns tonight, appearing as a wire-thin arc low in the northwestern sky. You'll need an open horizon to the northwest to see it. Start looking about 40 minutes after sunset or around 9:30-45 p.m. for the northern states. It's fun and instructive to imagine how the sky might look from the moon or another planet in the solar system. One thing wouldn't change -- the constellations. The stars are simply too far away to show any noticeable shift in the sky no matter what planet you're on. Even from icy Neptune you'd still see Orion's Belt and be able to use the Big Dipper to find the North Star.

Ah, to be an astronaut on the moon tonight! You'd see the nearly full Earth rising not far from bright Antares (red star) in the constellation Scorpius.

Other things change radically. We'll see the moon is in the constellation Taurus the Bull tonight, but put yourself on the moon and look back at Earth and you'll find our planet in Scorpius. Likewise with Mars. We see the dusty planet in morning twilight in Pisces the Fish, while the Martians would have a tough time finding Earth just now. From their perspective, we're in Virgo but too close to the sun to see in a dark sky. Check out the other gems in the neighborhood. As you can see from the map, Venus and Mercury are just a stone's throw away.

From Mars, Earth joins the company of Venus and Mercury near the star Spica in Virgo. The sky is black because I "removed" the Martian atmosphere so we could see the planets, which are all so close to the sun in Mars' sky they're lost in the glare of daylight.

I could go on but you get the idea. It's all about location, location, location.

Posted by: rking@duluthnews.com on 5/25/2009 at 10:04 AM | Comments (2) | Permalink

Return of the Milky Way

There was a whole going on near the Big Dipper during twilight last night (May 23). Details: 35mm lens at f/2.8, 1-minute time exposure at ISO 200. Photo: Bob King

Did you happen to see the International Space Station (ISS) pass through the Big Dipper last night? It was around 9:45 p.m. and though the sky was still blue with twilight, you could just make out the familiar form of the Dipper. While photographing the ISS, I didn't think I'd also record a sky high traffic jam. As the space station was passing out the frame to the right, another satellite briefly flared and left a short trail. At the same time, a flashing airplane crossed the field. All this in the space of just about a minute.

Much later the Milky Way rose up in the eastern sky. Just when I thought I was done for the night, that hazy band tempted me with more clusters and nebulas than I could shake an eyepiece at. The galaxy is the ultimate candy store for any skywatcher. Strewn along its misty arch is just about anything you'd ever want to see with the naked eye, binoculars or telescope.

I've marked the location of the Milky Way galaxy's center in this photo taken last night. Notice the dark splotches among the starry chunks. These are clouds of dust blocking the light of more distant stars. If you could vacuum all the dust out of the galaxy, the Milky Way would be bright enough to cast faint shadows. Details: 16mm lens at f/2.8, 35-second time exposure at ISO 1600. Photo: Bob King

Earth, sun and all the planets huddle together smack dab within the galaxy's flattened disk. When we look straight out and into the disk, the stars pile up over thousands of light years to form a thick band. Picture yourself standing in a field (the solar neighborhood) at the edge of forest (the greater Milky Way). As you look past the first few nearby trees, the more distant ones fill your field of vision until the impression is one of impenetrable forest. Something similar happens when we look into the Milky Way -- the stars pile up over great distances until they form a fog of unresolved light. This is the band of milky light we call the Milky Way. If you look away from the band, your gaze takes you above or below the disk, where there are far fewer stars.

A 360-degree panorama of the Milky Way taken from Texas (for the northern hemisphere half) and Australia (southern half). The blue box shows the section recorded in my photo last night. Credit: Digital Sky LLC

Early in the 20th century, astronomers learned that the galaxy's center was located in the constellation Sagittarius, better known as the Teapot. While the Milky Way is broad and bright in that direction, we can only see stars about one-fifth of the way to the center because of intervening dust. The dark rift splitting the Milky Way band in two is dust in the galaxy's plane left by generations of evolving stars. It absorbs the light of distant stars, giving the band a broken, lumpy appearance. Until telescopes were invented that could penetrate the dust and see into the core, no one had a clue what went on there. Thanks to radio and infrared telescopes, we now know that the Milky Way harbors at least one massive black hole at its center.


If you could rocket out of the Milky Way disk and look at it from above, you'd see our galaxy's bright core and multiple spiral arms. I have to believe some being somewhere must have this incredible perspective in their night sky. Credit: NASA/JPL-CalTech

As spring gives way to summer and Sagittarius becomes better placed for evening viewing, we'll revisit the Milky Way and its heart of darkness. For now, go to a dark place, stay up late and enjoy the return of the galaxy.

Posted by: rking@duluthnews.com on 5/24/2009 at 11:40 AM | Comments (4) | Permalink

May night masterpiece

The Great Hercules Cluster is a highlight of the spring sky and one of the brightest globular clusters. It can be found with binoculars and is a spectacular sight in amateur telescopes. See the hi-res image. Credit: Jim Misti

Like great works of art, there are some deep sky objects that skywatchers return to time after time, season after season. On each occasion you marvel at the sheer beauty of the thing or see something there you've never noticed before. One of my very favorite masterpieces goes by the humdrum catalog number of M13. It's a globular star cluster in the constellation of Hercules the Strongman.
 
M13 is also known as the Great Hercules Cluster and easily ranks among the Top Ten favorite sky objects for most northern observers. Your first impression on seeing it in a telescope -- and you'll need a 6-inch or larger scope for a good look -- is a glowing ball of tiny, densely-packed stars enveloped by starry whorls and tendrils. On a good night, the view is riveting. Just read Rhino's report in yesterday's comments.


Hercules is large and rather faint but the Keystone (circled) isn't too hard to spot. It's on a line between the bright stars Arcturus and Vega. Look two outstretched fists to the upper right of Vega or three fists to the lower left of Arcturus to get there. The map is drawn for around 10:30 p.m. looking northeast in a dark sky. Maps created with Stellarium. 

Globular clusters are enormous balls of stars held together by their mutual gravity. In the case of M13, the cluster packs over 100,000 stars into a sphere 150 light years across. The density of stars in its core is 100 times as great as in the sun's neighborhood, guaranteeing a night sky algow with hundreds of stars as bright as Jupiter and Venus.

In the book of galactic genesis, the first sentence might read like this: "In the beginning, there were the globulars, and they were most awesome." Globulars contain some of the oldest stars in the universe (12.7 billion years old) and probably pre-date the formation of our galaxy's disk. The Hercules cluster and about 150 other globulars form a grand halo around the center of the Milky Way galaxy in the direction of the constellation Sagittarius. If you want to hunt for these beauties, you typically wait for late spring and summer when Sagittarius enters the evening sky.

If you can find the Keystone, you're almost there. In this closer view, you can see that M13 is not quite halfway between the two stars on the west (top) side of the Keystone. Look for a little fuzzy ball that's obviously bigger than the stars around it. 

You don't have to own a telescope to see M13. I've seen it with my naked eye from the country and binoculars will pick it out with ease ... if you know where to look. I wish I could say there were bright stars to guide you to the cluster but you'll need a bit of a roadmap to get there. M13 is along the west (right) side of a four-sided figure called the Keystone of Hercules. Hercules is a large, dim, gangly constellation tucked between Vega and Corona Borealis (Northern Crown).

Using the maps, get there by first finding Arcturus, below the Dipper's Handle, and then moving to the left or north to the semi-circular Corona Borealis. The Keystone lies midway between Corona Borealis and brilliant Vega in the northeast. Look for dense little fuzzy spot framed by two small stars along the top side of the Keystone. 10x binoculars will help you to distinguish the brighter core from the fainter halo.

One of nature's greatest works hangs on the wall of spacetime 25,000 light years away. M13 awaits your gaze.

Posted by: rking@duluthnews.com on 5/23/2009 at 11:19 AM | Comments (0) | Permalink

Feeling a little wobbly today

I took this time exposure of the International Space Station (ISS) last night.
Notice that the color and brightness of the trail changes about 2/3 the
way down. The station fades and takes on sunset colors as it approaches and
then disappears into Earth's shadow. Astronauts  aboard the ISS see a sunset
about once every 90 minutes. You can see the color change yourself with just
a pair of binoculars. Scroll down to yesterday's blog for times to look this weekend.
Details: 35mm lens at  f/2.8, 25-second exposure at ISO 800. Photo: Bob King

Last night was calm and clear. I spent my time looking for galaxy pairs while listening to trilling toads shift back and forth between major and minor keys. I love the subtle pitch changes of their amorous song. Their music creates a sonic underpinning that keeps the night flowing along.

The Earth's wobbling axis describes a circle in the northern sky. The numbers with a minus sign are B.C., those with a plus are A.D. Thuban in Draco was the polestar around 3000 B.C. while Vega will be in 14,000 A.D. We live in the "Polaris era". Credit: Tao'lunga

Last March in this blog we talked about precession, the slight wobble of our planet's axis that causes the pole star to shift over time. One complete wobble takes 25,800 years. During that time our axis traces out an imaginary circle in the sky. Whatever star lies on that circle will perform "pole star duty" sometime during that long span of time. Polaris, also known as the North Star, is the pole's current resident. It's fairly bright and easy to find by shooting a line through the two stars at the end of the Bucket of the Big Dipper.

The North Star is the short, bright arc just below the center of the "whirlpool". The Earth's north polar axis points at the very center of the whirlpool, a spot called the north celestial pole. As our planet spins on its axis, the stars appear to describe trails around this point, creating a tunnel effect. Photo: Bob King

Polaris is very near but not exactly at the spot of sky our north polar axis points. Close inspection reveals that the North Star is some 1.5 full moon diameters away from exact center. That's close enough to appear motionless in the sky to our eyes. Just for fun, I pointed my 200mm telephoto at Polaris and made a 20 minute time exposure. A quick glance at the picture shows that the North Star is slightly offset from true north. If it were possible to continue the exposure for 24 hours, you'd see Polaris describe a small circle about the pole point.

As Earth's axis continues its cyclic wobble, it will bring Polaris ever closer to the pole point. Closest approach will occur around the year 2100 when it will be just one moon diameter away. By and by, Polaris will be replaced by another polestar. The next obvious one will be the star Gamma in the constellation Cepheus the King around 4000 A.D.

You can find the house-shaped constellation Cepheus (SEE-fee-us) between the W of Cassiopeia and the North Star. The star Gamma will become the new polestar 2000 years from now. The map shows the sky around 10-10:30 p.m. as you look north. Created with Stellarium.

Polaris will return to duty around 28,000 A.D. Think how ancient today will seem to our distant descendants. 28,000 years ago the last of the Neanderthals were still living in what is now southern Spain. Perhaps they knew Polaris too.

Posted by: rking@duluthnews.com on 5/22/2009 at 1:57 PM | Comments (2) | Permalink

Love song for a smelly planet

You can't always get what you want, but you can get what you need. I got some needed sleep last night but I wanted to see the moon, Venus and Mars this morning before sunrise. Clouds nixed the view. I trust a few of you faired better.

Last night we were suddenly yanked into summer. The wind shifted and hot air rushed in from the south shooting temperatures into the 80s. Even at night it was still 75 degrees, and the air was filled with fragrances of balsam poplar, rain on asphalt, particle board, grass, distant skunk, bog, damp cement, spruce needles and chokecherry flowers. On a humid night, smells are as intense as scenes.

A crack between clouds allowed a brief view of Saturn in the darkening sky. Nearly a billion miles away, the planet hinted at the bitter cold of space. As the opening closed, little drops of rain began falling, wetting my fingertips and cheeks. Quasars and star clusters may draw my attention night after night but I love this stinky planet more than anyplace.

A time exposure of a flare from the Iridium 29 satellite taken last Thursday at 3:15 a.m. The Big Dipper's at right. Credit: Lyle Anderson

We got a nice photo submission this week from Lyle Anderson of an Iridium flare. Thanks Lyle! International Space Station (ISS) watching has been excellent for more than a week and will continue for at least another. Here are some times to watch for passes. In each, the station will "rise" in the west-northwest and move eastward across the sky.

* Tonight May 21 at 8:54 p.m. and again at 10:30 p.m. The latter pass is nearly overhead and will be extremely bright.
* Friday May 22 at 9:20 p.m. and again at 10:55 p.m.
* Saturday May 23 at 9:46 p.m. and 11:22 p.m. The earlier pass will be another brilliant one.
* Sunday May 24 at 10:12 p.m.

Those of you with telescopes, consider trying to catch the ISS on a high pass using your low power eyepiece. It might surprise you how easy it is to see the orange solar arrays sticking out of the shiny "core" of the station. They're quite striking at a magnification of 64x and should be visible at even lower powers.

Video of the ISS taken through a telescope last May by Dirk Ewers

The hard part is catching a fast-moving object in the telescope's narrow field of view. I follow the space station first through a 10x finderscope (equipped with crosshairs) attached to the main telescope so I can get a feel for its speed and direction of travel. Then I position the crosshairs at the spot I anticipate the station will pass, and quickly swing back to the telescope, hoping to spot it before it's gone.

I missed it the first few times but gradually my success rate became more respectable. Once you have the space station in view, all you do is track it as smoothly as possible by hand while trying your best to discern its curious shape. Another way to do it, is to get a friend to sight it through the finderscope while you look through the eyepiece. If you don't get your eye poked out, it's much fun.

There are telescope mounts and software that allow you to do this with ease but the old-fashioned way works too.

Posted by: rking@duluthnews.com on 5/21/2009 at 1:13 PM | Comments (4) | Permalink

Killer Milky Way video and a gorgeous gathering

One of our readers wrote me yesterday about this wonderful time lapse video of the night sky as it passed over the 2009 Texas Star Party in Fort Davis, Texas. Created by William Castleman, it's a compilation of 20-second time exposures made with a fisheye lens and spanning an entire night. The Texas Star Party is one of the premier events of the year for amateur astronomers who want to observe in some of the darkest skies in the country.  

Castleman focused on the Milky Way rising but his video shows other interesting happenings:
* the red glow of amateurs' flashlights as they find they navigate their star maps.
* a faint diagonal band of light best seen about halfway through the video. This is the zodiacal band and gegenschein, a layer of dust in the plane of the solar system dimly lit by the sun. 
* Meteors
* Notice how the Milky Way looks reddish as it rises and then becomes whiter. It's red for the same reason the sun and moon are red when they're near the horizon -- blue light is scattered away from the sun by the atmosphere. Only the oranges and reds can penetrate the thick air without getting bounced about.

Look low in the northeastern sky Thursday morning (May 21) to see a celestial triangle of moon and planets. This map shows the sky looking east about an hour before sunrise or around 4:30 a.m. for northern Minnesota. Created with Stellarium.

Yesterday I alluded to a very nice arrangement of moon and planets visible in tomorrow morning's dawn sky. The thin crescent moon will form a nifty triangle with brilliant Venus and dim Mars during twilight. To see the show, head out about an hour (maybe a little earlier if you have wide open horizon to the northeast) and first spot the moon and Venus. Mars should be visible to the naked eye but pack binoculars just in case. Thanks to the moon, this will be a fine opportunity to see Mars again after a  long absence.

Jupiter will be only about one full moon diameter from Neptune for the next couple weeks -- very close. Neptune will look like a dim star above the giant planet. Jupiter moves eastward (left) during the time, and together with the star Mu, will form a variety of triangle figures with the distant planet. Although they appear close together, Neptune is 2.8 billion miles away, six times as far as Jupiter is from the sun. Created using Skymap software by Chris Marriott.

Further off to the southeast, you'll see Jupiter blazing away in the constellation Capricornus the Sea Goat. Starting tomorrow and continuing for well over a week, Jupiter will serve as a bright guide to the planet Neptune. Under reasonably dark skies, Neptune is fairly easy to see in 7x50 or 10x50 binoculars. Use the map above to point you there and go out before twilight begins when the sky's still dark. Luckily, there are few stars in the neighborhood to cause confusion, making this a great opportunity to see the solar system's most remote planet.

Small telescope users can see three of Jupiter's moons Thursday parked up directly under the star Mu Capricorni. Mu is a faint naked eye star but very obvious in binoculars and telescopes. *Note: Your view might be flipped upside down or side to side depending on what kind of telescope you're using. Created with Stellarium.

Posted by: rking@duluthnews.com on 5/20/2009 at 10:46 AM | Comments (0) | Permalink

Martian separation anxiety

Mars has some of the most otherworldly landscapes in the solar system. I thought it would be fun to look at a few recent photos taken by the orbiting Mars Reconnaissance Orbiter. My ulterior motive is to inspire you to set your alarms this Thursday morning for a delighful triangular gathering of crescent moon, Venus and Mars.

Mars is not particularly close to the Earth this month, nor bright. It's been struggling to separate itself from the eastern horizon and the bright light of dawn since winter. That's made it harder to find than a good tomato.

Since the planet is much closer to the Earth and the sun than say, Jupiter and Saturn, its orbital speed is much faster. As Mars races eastward in the sky, it keeps pace with the sun and the dawn, taking what seems like forever to emerge again in a dark sky. Only when Earth begins to catch up with Mars, which it will do later this year, does the planet finally overcome its solar separation anxiety and return to easy viewing. The outer planets also orbit eastward but much more slowly, allowing the sun to leave them "behind" in a dark sky much sooner.

Tomorrow I'll provide viewing tips, maps and more to help you get back in touch with the Red Planet. In the meantime, enjoy the views. For many more, check out NASA's Planetary Photojournal.

Persistent easterly winds blowing from right to left off the two flat-topped mesas (right) and surrounding landscape have created spectacular chains of sand dunes called barchans (BAR-kens). Similar-shaped dunes are found on Earth. The white landform at upper left is a dome-covered hill. The steady east winds are part of the transition from spring to summer in Mars' southern hemisphere. Click here for a hi-res photo. Credit: All photos taken by the Mars Reconnaissance Orbiter/LPL/NASA


Diagram showing how barchan dunes form. The distintive droplet shape is caused by the avalanch of built-up sand on the downwind side of the dune. Barchans can be many hundreds of feet wide. Credit: Wikipedia

Rounded landforms on the frozen carbon dioxide surface of Mars' south polar ice cap. They take shape quickly but then erode back into the surface at the rate of 15 feet per year. Credit: NASA/JPL/U. of Arizona


Mars has two moons -- Phobos and Deimos. This photo shows two views of the rarely photographed Deimos, one of the smallest known moons in the solar system with a diameter of only 8 miles. Credit: NASA/JPL/U. of Arizona

Posted by: rking@duluthnews.com on 5/19/2009 at 12:35 PM | Comments (0) | Permalink

How a little girl named a planet

This time-exposure photo from last night shows the faint trail of the Earth-sensing satellite Envisat next to the Big Dipper. For more on Envisat, see yesterday's blog. Photo: Bob King

Did you try to find Envisat last night? If you did, you were probably as surprised as I at how faint it was. Sure, things started well enough. The satellite appeared on time near Arcturus but it was a level fainter than the prediction. By the time it rose to meet the Big Dipper, Envisat was almost too faint to see. I took a photo anyway and you can just pick out the threadlike trail in the upper left half of the frame. Why so dim? I wish I knew the answer. I deliberately picked Sunday's pass because it was a bright one. Perhaps the satellite was pitched to a side that didn't reflect light as well. Good thing the space station was out at the same time -- its bright pass made up for what the other lacked.

On April 30 this year, the woman who named Pluto passed away at her home in England at 90. Venetia Burney Phair was only 11 years old in 1930 when Pluto was discovered. It all started with a "Planet Walk" at Burney's school in Oxford, England. The class drew a 2-foot diameter circle on the blackboard to represent the sun, then walked outside and placed their planets, represented by a pea (Earth) up to an orange (Jupiter) at various locations on the school grounds.

As part of her studies, Venetia (at left) also knew a little Greek mythology. On March 14, 1930 she was sharing breakfast with her grandfather Falconer Madan when he read aloud the news about the discovery of a new planet by American astronomer Clyde Tombaugh. The article mentioned that the planet had not been named. Venetia listened and then quietly turned to her grandfather and said: "I think Pluto would be a good name for it."

Pluto was the Roman god of the underworld. Burney's suggestion was very intuitive because a planet as distant as Pluto would be in a dark, faraway place in the solar system.

Grandpa Madan was very impressed with Venetia's suggestion so he passed it along straightaway to his friend, Herbert Hall Turner, professor of astronomy at the University of Oxford. Turner then cabled the name to Tombaugh at Lowell Observatory in Flagstaff, Arizona.

Tombaugh (at right) liked the name because its first two letters were those of Percival Lowell, who had predicted the existence of the new planet. After numerous other name suggestions including Kronos, Zeus, Minerva, Lowell and even Constance (suggested by Lowell's widow, Constance Lowell), the name Pluto was formally adopted on May 1, 1930.

As a sign of appreciation for his granddaughter's suggestion, Falconer gave her a five-pound note, the equivalent of $350 in today's money.

Venetia, who married in 1947, went on to become a teacher of economics and mathematics at girls' schools in southwest London. She always kept abreast of what was happening with the little planet she'd named. As for how she felt about the change in Pluto's status from planet to dwarf planet, she was indifferent but supposed she'd rather see it as a planet. You can read more here. And just to keep the record straight, Pluto was not named after the Disney character. The dog was named later.


Pluto and three of its moons as photographed by the Hubble Space Telescope in 2006. Credit: NASA/ESA

The New Horizons spacecraft is now en route to a Pluto flyby on July 14, 2015. On board is an experiment that maps the sizes and locations of dust particles the craft encounters along its journey. In honor of Venetia Burney Phair, the instrument was recently renamed the Venetia Burney Student Dust Counter. Like a tiny light in the underworld, her spirit is heading to the world she named.

An artist's view of Pluto (foreground) covered in methane ice. Just above the horizon to the left Charon, the planet's largest moon. At upper right is the tiny and distant sun. Pluto's surface temperature is 400 below zero and it's approximately four billion miles from the sun. Credit: ESA, L. Calcada

(Venetia image credit BBC archives. Tombaugh from Lowell Observatory Archives)

Posted by: rking@duluthnews.com on 5/18/2009 at 1:48 PM | Comments (0) | Permalink

Eyes to watch our world

A photo of Lake Superior and northern Lake Michigan taken by Envisat in October 2007 showing fall color well underway. Credit: ESA

What measures the temperature of the sea's surface, studies the air by watching stars descend through the atmosphere and recently took a disturbing photo of an ice shelf collapsing in Antarctica? It's the European Earth-monitoring satellite Envisat, and you can see it in the sky tonight. Envisat was launched in 2002 by the European Space Agency (ESA) and has been studying our planet from an orbit nearly 500 miles high. Its primary mission is to monitor changes in the ocean, sea ice and atmosphere. To learn more, take a look at the Envisat Mission Page. You can also go straight to an image gallery if you like.

This map shows the sky as you'd see it lying flat on your back tonight (Sunday) with your feet facing east. Envisat will be at its brightest along the length of the green track. At 10:25 p.m. Central time watch for the satellite near Arcturus. About a minute later it'll pass very close the end of the Big Dipper and then near Polaris, the North Star. Created with Stellarium.

The satellite makes regular passes over the U.S. and Europe, and tonight's will be one of the brighter ones. As Envisat rises up from the eastern sky, it'll pass right next to brilliant Arcturus and then tickle the Handle of the Big Dipper. They'll serve as perfect guides for tracking it across the top of the sky. Watch for a "moving star" of 3rd magnitude or one step fainter than the stars of the Dipper.

As you lay back with hands cupped behind your head, who knows, maybe Envisat will be looking back at you.

An artist rendition of Envisat in orbit around the Earth. It's about 80 feet long and orbits Earth once every 101 minutes. Credit: ESA

Posted by: rking@duluthnews.com on 5/17/2009 at 12:51 PM | Comments (0) | Permalink

Check out these cool pix of Hubble and Atlantis

The NASA video (above) shows just how busy the near-Earth space environment has become with communications, sensing, spy and science satellites since the Russians launched Sputnik in 1957. No matter where we go, we humans have a knack for leaving a trail. The video takes you through the year 2000.

Just this Wednesday a fist-sized piece of space junk passed within a couple miles of the space shuttle Atlantis. The chunk was one of the pieces of the Fengyun-1C satellite that was blasted to bits by a Chinese anti-satellite weapon in January 2007. NASA's Orbital Debris Program Office estimates there are now 150,000 pieces of debris larger than 1/2" from the event. Ground controllers track the larger fragments and alert the crew if one is coming their way so they can maneuver their ship to safety.

Astronauts service the HST this week from aboard Atlantis. Credit: NASA

You've probably heard that the Hubble Space Telescope (HST) repair mission is going very well. The scope now has fresh batteries for power storage and new gyroscopes to help it point accurately. As I write this, the astronauts are busy this morning installing the Cosmic Origins Spectrograph, an instrument for studying the structure and evolution of galaxies in ultraviolet light. While they're out there for 6 1/2 hours concentrating on their tasks, think of the view of Earth they'll have when they stop to take a breather.

See anything interesting in this photograph of the sun by astrophotographer Thierry Legault? For a close up of that speck of dirt at lower left, see below. Credit: NASA/Thierry Legault

In this cropped view, you can make out the space shuttle Atlantis alongside the smaller Hubble Space Telescope. The two craft crossed the face of the sun at 11:15 a.m. Central time Wednesday as seen from west of Vero Beach, Florida. Credit: NASA/Thierry Legault

Amazing photos, aren't they? At the time, the two were 373 miles high and crossed the sun in only 0.8 seconds. Thierry made this photo with a 5-inch refracting telescope equipped with a solar filter, a digital camera and excellent planning. To see more photos, take a look at his astrophotography website.

The stars that were once so dominant in winter are now passing into the west. Go out in late twilight for one of your last chances to see some of the best and brightest stars (yellow) and constellations (red) of the winter season. This map shows the sky as you look west around 10 o'clock tonight. Created with Stellarium. 

Posted by: rking@duluthnews.com on 5/16/2009 at 9:14 AM | Comments (2) | Permalink

How much is that galaxy in the window?

A home along East 5th Street features a poster of a well-known
galaxy. Photo: Bob King

I usually start my workday mornings with a drive around town to look for photos for use on the Duluth News Tribune website. Yesterday morning, I turned a corner and drove down East Fifth Street. There in a window was a large black and white poster of a familiar galaxy. I've been up and down every street in Duluth over the years and have seen political, patriotic, religious, rock band, radio station and all manner of sale and community announcement signs propped in windows and set up on front lawns. This was my first galaxy.

Whoever put the poster up wanted people walking or driving by to notice it, so it's a fair assumption they find galaxies as amazing as you and I do. Their choice was a good one -- the spiral galaxy NGC 891 in the constellation Andromeda. It's ghosty and faint in a modest amateur telescope but that dust lane silhouetted against the billions of stars comprising the galaxy's core and disk is a visual delicacy.

NGC 891 was first seen by William Herschel, the same person who discovered the planet Uranus, back on October 6, 1784. Nicknamed "The Cigar Galaxy", this smokin' stogie is 30 million light years from Earth and speeding away from the Milky Way at 328 miles per second.

Space between the galaxies has been expanding since the Big Bang started it all 13.7 billion years ago. Over time, galaxies have been moving away from us -- and from each other -- at speeds proportional to their distances. While the Cigar's speed seems high, astronomers have clocked the most remote galaxies burning rubber at a significant fraction of the speed of light.

American astronomer Edwin Hubble, who discovered cosmic expansion. He determined that the further out in space we look, the faster the galaxies are moving away. Credit: NASA

43 miles per second per 3.26 million light years. That bit of math goes by the fancy name of Hubble's Constant, and it's how fast most galaxies are receding from our home galaxy the Milky Way. What it means is that for every 3.26 million light years of space, galaxy speeds go up another 43 miles per second. Simple multiplication shows that a galaxy that's 30.26 million light years away would be receding from us at about 430 miles per second (individual galaxies or those in clusters can vary some). Since the most remote galaxies are upwards of 13 billion light years away, those numbers quickly add up to incredible velocities. 

Keep in mind as you visualize flying galaxies, that space itself is expanding between the galaxies, not that galaxies are hurtling on their own power through a set volume of space. Like blowing up a balloon that never pops, the universe keeps getting larger every day.
 
I drove up, stopped, got out of the car, took a photo of the NGC 891 poster, got back in the car and left. In that brief interval the galaxy sped over 10,000 miles further from Earth.

Hold onto your hat!

Posted by: rking@duluthnews.com on 5/15/2009 at 11:41 AM | Comments (2) | Permalink

There be dragons here

Everyone needs a dragon in their life. Since there are so few to be found, we're fortunate to have one in the northern sky visible most nights of the year. Draco the Dragon coils between the Big and Little Dippers and onward toward the bright star Vega. Although consisting of mostly dim stars, Draco's in relatively easy to find thanks to its stellar company.

Draco winds between the Dippers in the northern sky. This map is drawn for 10 p.m. as you look due north. The end of the dragon's tail is high in the north while the head is low in the northeast. The star Nu is a sweet double star for binoculars. Created with Stellarium.

Look for the Big Dipper, which is nearly overhead when the sky's dark around 10 o'clock, and begin with the the end star in the Bucket. The first star you see below it is the tip of the dragon's tail. From there, follow the gentle curve of stars that form the sinuous body, bend left toward the North Star and then make a right and head toward Vega. Draco's head is the little box of four stars just to the left and above Vega. The faintest star in the dragon's head is called Nu Draconis, and it's one of the best binocular double stars in the sky. Give it a look the next clear night.You'll be able to easily distinguish two nearly identical white stars sitting side by side. The pair is located 100 light years from Earth.

Draco represents a mythological dragon and its constellation stars bear a good resemblance to a real one. Hold on, are there any real dragons?? Credit: Alexander Jamieson/Urania's Mirror

Although the map makes Draco look modest in size, it's really a big constellation spanning at least three outstretched fists from head to tail. The dragon is one of the few constellations that bears a close resemblance to the figure it represents. Within its boundaries are lots of double stars and galaxies. Two of the most interesting telescopic objects are the galaxy M102 and a planetary nebula nicknamed the Cat's Eye. We looked at M102 in a blog last week. The Cat's Eye, also known by its catalog number NGC 6543, is one of the brighter planetary nebulas. This class of nebulas got its name because they're often round with a distinct border much like a planet. Otherwise they have nothing to do with planets.

The Cat's Eye nebula (left) and the galaxy M102. You can see the white dwarf central star in the nebula and numerous concentric shells of gas. The dark line in M102 is dust in its equatorial plane that neatly splits the galaxy into two. Credit: NASA/ESA/Hubble Space Telescope.

Look at all those shells of material around the bright center. Those are clouds of gas expelled over thousands of years by the white dwarf star at the nebula's center. As stars in the sun's size-range evolve, they eventually puff up to become huge gas bags called red giants. When the sun becomes a red giant, it will engulf Mercury and Venus and perhaps even the Earth. Over time, much of that gas is expelled into space by the fierce heat and hot wind coming from the star's center. Several billion years from now, what you're left with is the sun's core, now a white dwarf star, surrounded by its former outer layers. The tremendous energy radiated by the dwarf sets the outer shells aglow creating a colorful cosmic ornament.

Planetary are very beautiful, especially when photographed through large telescopes. Will the sun look so pretty in old age?

Here is a list of times for catching a pass of the International Space Station (ISS) for a large region around Duluth-Superior. The ISS generally first appears in the western sky and moves eastward. A typical pass is about 4-5 minutes long.

* Thurs. May 14 starting at 9:03 p.m. in twilight. Brilliant, overhead pass! Second pass at 10:39 p.m. across the north.

* Fri. May 15 at 9:29 p.m. and again at 11:05 p.m. across the north.

* Sat. May 16 at 9:56 p.m. and 11:31 p.m. across the north.

* Sun. May 17 at 10:22 p.m. and 11:57 p.m. across the north.

Posted by: rking@duluthnews.com on 5/14/2009 at 1:18 PM | Comments (4) | Permalink

Wait -- how old was that again??

The Pachal Paran of the Negev Desert, the location of the oldest, vast area of Earth's surface. Credit: Mark A. Wilson

How old is the oldest large-area surface on Earth? I never even considered the question until coming across an article last week about a team of Israeli, French and U.S. scientists confirming that the Israel's Paran Plain in the Negev Desert clinches the title. Its surface is estimated to be 1.5-1.8 million years old, four times older than the previously known oldest region in Death Valley in Nevada.

Most surfaces are much younger because of erosion, weather and tectonic activity like earthquakes, mountain building and volcanoes. Individual rocks and rock formations however have much older dates. The record holder for the moment are rocks found along the eastern shore of Hudson Bay in northern Quebec. These date back to 4.28 billion years, only 17 million years after the Earth's crust formed 4.5 billion years ago. Some tiny mineral grains from Australia have been dated to 4.36 billion years, but no complete rocks older than the Canadian ones have been found.

Scientists use the decay rate of radioactive isotopes to detemine a rock's age. Elements like uranium are naturally unstable and decay into other elements at a specific rate called a half-life. Uranium-238, the most common form of uranium in uranium ore, has a half-life of 4.5 billion years. That means that half of the uranium atoms will decay to form lead, which is stable, in 4.5 billion years. Another half of what's left will turn into lead in another 4.5 billion and so on. Over the ages, the amount of uranium decreases while lead increases.

Scientists detemine age by comparing the initial amount of uranium 238 and lead in the rock to the ratio measured today. Zircon is the mineral most often used. When zircon crystallizes, it's very friendly to uranium but strongly rejects lead. The only way for lead to get inside the crystals is through uranium decay. It's very straightforward then to measure the amount of lead present, compare it to the uranium still left and then derive an age.

Here's another way to think about radioisotope dating. If you start out with no money and I give you a $10 bill every eight hours, a third party would know how long ago I started handing out the bills just by counting how many tens you have in your wallet. For more on the isotope dating method, check out this site. Other elements like rubidium- strontium, with a half-life of 50 billion years, can help date materials even more ancient.

Jack Schmitt, Lunar Module Pilot on Apollo 17, works with the lunar rover in the moon's Taurus-Littrow Valley. The valley's surface is about 3.7 billion years old. Credit: NASA

1.8 million years is certainly a long time by human standards, yet much of the moon's surface is at least 3.7 billion years old, more than 2000 times older than the Negev. Go just about anywhere you like on the moon and you'll be standing on mountains, plains and craters that formed at least a billion years ago. The oldest rocks brought home by the Apollo astronauts take us back 4.46 billion years. They were among the first rocks to crystallize on the molten lunar surface. Those were the formative days of the solar system, when planets and moons were shaped from the incessant bombardment and capture of meteorites and asteroids.

A slice of a carbonaceous chondrite named NWA 3118 with a white CAI (calcium aluminum inclusion) circled. The other bead-like objects are called chondrules and are nearly as old as the CAI. Most meteorites contain the most ancient solid matter in the solar system. Photo: Bob King

Those few moon rocks, while very ancient indeed, are still not the oldest solid stuff in the sun's neighborhood. A certain class of meteorites called carbonaceous (car-bon-NAY-shuss) chondrites (KON-drites) contain small, irregular white patches of a mineral made of calcium and aluminum. These have been dated to 4.56 billion years ago, and are the first solids to congeal from the original cloud of gas and dust that evolved to form the sun and the planets. Think of them as solidified rock vapor deposited in space as tiny grains by generations of stars that shone before the sun.

Old as it is, we've come a long way from the Negev.

Thinking of the oldest surface makes one wonder what might be the youngest. I'd vote for the surface of a lake like Superior. Not only is it in constant motion, but lakes are constantly losing water through evaporation and getting it back through streams and precipitation. Part of the city of Duluth can be seen in the background in this photo. Photo: Bob King

Posted by: rking@duluthnews.com on 5/13/2009 at 1:12 PM | Comments (2) | Permalink

Shadowmobile eclipse

Our car shadow keeps pace along I-35 yesterday near sunset. The sun was off to the left and behind us when the picture was taken. Photo: Bob King

My daughter and I were driving back from St. Paul this weekend and as we approached Duluth, the sun was near setting. Both of us looked out the window and were tickled to see the shadow of the car cast on the occasional embankments we passed. Because the sun was so low, we could see the complete shape of the car all the way down to the wheels. It felt a little eerie to watch a two-dimensional version of us speeding along the roadside in our shadowmobile.

The moon as it orbits the sun occasionally casts its narrow shadow on Earth, creating a brief total solar eclipse. Credit: Sagredo

Our shadow was created by the simplest of alignments: sun-car-embankment. This very same arrangement is responsible for one of nature's most awesome events that few of us ever get to see -- a total eclipse of the sun. There the layout is sun-moon-Earth. As the moon travels in its orbit around the Earth, a couple times a year it aligns precisely between our planet and sun, casting a shadow some 150 miles across a narrow strip of Earth's surface.

This remarkable photo shows the moon's shadow over Europe during the total solar eclipse of August 11, 1999. It was one of the last pictures taken aboard the Mir space station which was deorbited in 2001. Saturn and Jupiter are at upper left. Credit: Mir 27 crew. Copyright: CNES

Like my car, the moon is moving too, but much faster at 1240 miles per hour. If you happen to live under the shadow path, you'll see the moon cover the sun completely but only briefly. The moon moves on. We did too. We watched our budget eclipse from the car's point of view until the sun set. Meanwhile the crickets and ticks inhabiting the grass got to experience a very short total solar eclipse as the car shadow zoomed by at 70 mph.

A 30-second time exposure of the 10:56 p.m. pass of the International Space Station last night. I added the names of a few bright stars and the Beehive Cluster in Cancer. Near the bottom, you can see the trail of an airplane that crossed the view at the same time. Photo: Bob King

Did you catch any of the International Space Station (ISS) passes last night? We had two -- one during twilight and another just before 11 o'clock. Tonight the ISS will return for two passes. The first pass, very high and bright, will begin at 9:47 p.m. with a second one at 11:22 p.m. Tomorrow I'll update passes through the remainder of the week.

Happy viewing!

Posted by: rking@duluthnews.com on 5/12/2009 at 11:30 AM | Comments (2) | Permalink

Hubble towed in for a refurb

The Hubble Space Telescope orbits some 370 miles above the Earth, high above most of our planet's atmosphere. The scope has fallen into disrepair and NASA almost wrote it off. Fortunately the agency reconsidered and planned one last mission to bring it back up to snuff. Credit: NASA

The space shuttle Atlantis successfully blasted off this Monday afternoon from the Kennedy Space Center on an 11-day mission to repair and upgrade the Hubble Space Telescope (HST). The telescope has been in orbit since the spring of 1990. High above Earth's fluttering atmosphere Hubble observes stars, planets and distant galaxies with a precision that until recently was unobtainable even by the largest ground-based telescopes.

When you go out at night and admire the twinkling stars, you already understand one of the two main reasons Hubble does its work from space. Twinkling is caused by shifting air currents that smear and distort stars and galaxies, putting a limit on how sharply astronomers can see their targets. Get above the air and the twinkling's gone. Images are rock steady.

A tiny sample of photos taken by the Hubble scope. Clockwise from left: A spire of gas inside the Eagle Nebula, a stellar nursery in our Milky Way; auroras at one Jupiter's poles; the galaxy M82, site of intense star formation and a strand of gas from a supernova explosion in 1006 A.D. (Links take you to amazing, hi-res images.) Credit: NASA/ESA

The atmosphere also blocks or absorbs certain kinds of light like ultraviolet and infrared. Stars, planets and galaxies emit light across the entire electromagnectic spectrum, of which visible light is just a small part. If we're going to uncover remote galaxies that formed just after the Big Bang or discover auroras on Jupiter, we have to expand our vision into other parts of the spectrum. Going into space is like removing a veil from our eyes. Hubble can see into the ultraviolet and infrared (heat energy) and reveal new facets of a galaxy's or star's personality with great precision.

The layout of the HST. Credit: NASA

A 94-inch primary mirror that gathers light just like a reflecting telescope you can buy right here on Earth is at the heart of Hubble. It's hooked up to cameras and a spectrograph, an instrument that breaks down light into its component colors to determine the composition of a star, its temperature and speed through space. Hubble is used continuously by astronomers here on Earth and records about 10 gigabytes of data per day. That would fill up the home computer's hard drive in a week!

The HST is 43 feet long, or about the size of a school bus, and 13 1/2 feet in diameter. The solar panels, used to charge the onboard batteries, are 23 feet long. HST's orbit around the Earth is inclined 28.5 degrees to our planet's equator and it goes around the globe once every 96 minutes traveling at 17,398 mph. Because its orbital tilt is considerably less than the International Space Station, Hubble never pokes its head above above the horizon for the northern U.S. I once saw it from South Carolina and recall it looked about as bright as a Big Dipper star.

The space shuttle Atlantis will first rendevous with Hubble, then pull it into the payload bay with the robotic arm (white tube on the right side of the shuttle). The repairs and new equipment installation will require five spacewalks. Credit: NASA/ESA

Here's a laundry list of some of the work that the astronauts will perform on the Space Telescope. When they're done, Hubble will once again a lean, mean, data-digging machine through at least 2014:

* Replace batteries - the current ones are 18 years old.
* Replace the blankets that protect the craft from radiation and debris.
* Install a new instrument called the Cosmic Origins Spectrograph to study ultraviolet light from very distant objects. The instrument will help determine the large scale structure of the universe and the formation of elements like iron and carbon that are crucial for life.
* Install the new Wide Field Camera 3 for observing in visible, ultraviolet and infrared light over a greater range and with a wider view and higher resolution. Among other things, the camera will study water and ice on Mars.
* Install six new gyroscopes to help point the scope accurately.
* Install a "soft capture mechanism" that allows a robotic craft to attach to Hubble and guide it through reentry and burnup in our atmosphere when that time finally comes.
* Repair a current spectrograph and camera. Replace guidance sensors and a data handling unit.

For more information on Hubble, go to the Hubblesite or the excellent and comprehensive  NASA/ESA Hubble Space Telescope website.

Posted by: rking@duluthnews.com on 5/11/2009 at 11:19 AM | Comments (1) | Permalink

Fiesta Galactica

With the moon past full, dark skies return again to the evening hours. The moon really takes over the sky, especially around full phase. On a walk the other night I noticed that only stars as faint as third magnitude (one brightness level below those of the Big Dipper) were readily visible. Fourth magnitude took a lot of effort and fith was out of the question. Tonight many hundreds more stars all the way to sixth magnitude will be visible for a brief spell before moonrise. Since the moon rises about an hour later each night, the amount of "dark sky time" keeps increasing through the upcoming week.

The Sombrero Galaxy is located in the constellation Virgo. It contains some 800 billion stars, twice as many as our Milky Way galaxy. The bright bulge consists of mostly older stars while the disk and spiral arms are composed of stars, gas and dust. The stunning dark dust lane is visible in a modest telescope. See a larger photo. Credit: ESO/IDA/Danish 1.5 m/R. Gendler and J.E. Ovaldsen

One of the lovliest galaxies in the spring sky, and one that's ideally placed for viewing in dark skies, is the Sombrero in Virgo. You can see from the photo how the Sombrero got its name. Its central bulge of unresolved stars is surrounded by a broad, flat brim of dust. To find it, you can start with the Big Dipper. Follow the arc of the Handle down to Arcturus and continue to Spica. Just to Spica's right is the squarish figure of Corvus. The galaxy is about one binocular field of view above Delta, the star in the upper left corner of Corvus.

This map shows the sky looking south around 10 o'clock this week. To find our featured galaxy in binoculars or telescope, take Arcturus, high in the southeastern sky, down to Spica and from there to Corvus. Click here for a map to get there starting from the Big Dipper. Maps created with Stellarium.

You can see the Sombrero as a faintly glowing patch in binoculars from a reasonably dark sky. Any telescope will also show it but to see the bulge and dust lane, you'll need an 8-inch or larger scope. The Sombrero was discovered in March 1767 by French astronomer Pierre Mechain and eventually incorporated into comet hunter Charles Messier's catalog of "fuzzy things in the sky" as entry number 104 or M104.

Once you're at Corvus, take your binoculars and point them one field above Delta, the upper left star of the Corvus figure. A very handy arrow of stars, shown in red, will point you to the Sombrero. A pair of 10x50s should show a fuzzy spot.

At 30 million light years away, M104 is relatively nearby as galaxies go. Its most striking visible feature is the dark lane of dust left by generations of exploding and evolving stars within the galaxy's spiral arms. Through a modest telescope, it looks so straight it seems a bit unreal. Invisible to the eye but just as amazing is what lurks in the middle of that enormous bulge.

Data from the Hubble Space Telescope and others show that stars are revolving much too fast around the center of the galaxy to stay in place. By all rights, they should fly off into space. They're not because something with a mass a billion times greater than the sun sits at the center and holds them in orbit. What is it? A supermassive black hole. Only a black hole has that kind of pull while at the same time being invisible in even the largest telescopes.The Sombrero's is one of the most massive black holes in any nearby galaxy.

M104 was also the first galaxy to show a large redshift, an indicator that it's moving away from us at a high rate of speed. Work on this was done back in 1912 by Vesto Slipher at Lowell Observatory in Flagstaff, Arizona. His data was used by astronomer Edwin Hubble in the 1920s to show that our universe was not sitting still but rather expanding at an increasing rate the farther in space we look. Little bits of data like Slipher's eventually changed our whole perception of the cosmos.

It's all there for your viewing and contemplation the next dark night. Keep those binoculars handy.

Posted by: rking@duluthnews.com on 5/10/2009 at 9:55 AM | Comments (4) | Permalink

60,000 orbits and still cruisin'

Backdropped by the blackness of space and Earth's horizon, the International Space Station is seen from Space Shuttle Discovery. To enjoy a high resolution version of this photo, click here. Credit: NASA

The International Space Station (ISS) will begin a new series of evening passes across the U.S. starting this weekend. For the Minnesota-Wisconsin region, I've listed times to watch below. If you live outside this area, click here and just type in your zipcode to get times for your neighborhood.

ISS Expedition 19 Flight Engineer Koichi Wakata floats in the Zvezda service module of the International Space Station earlier this week. Wish I could float at work too. Image Credit: NASA

On Sunday at 4:58 a.m. the station will begin its 60,000 orbit as it soars over the Pacific. Since the launch of its first element on Nov. 20, 1998, the station's mass has grown to more than 669,000 lbs., with over 12,5000 cubic feet of living space. A quick calculation shows that 60,000 orbits comes to over 1.5 billion miles of travel, nearly the distance to the planet Uranus.

Watch for the first good ISS pass on Sunday night. It will appear as a bright star rising in the western sky and traveling eastward across the northern sky. Try to follow the full pass because you might get to see a bright flare of sunlight from one of the station's many solar panels. The panels generate the power the ISS needs to operate.

 * Sunday May 10 starting at 10:30 p.m. in the southwestern (SW) sky and traveling to the northeast (NE). The ISS will  be brilliant as it passes nearly overhead.

* Monday May 11 at 9:22 p.m. and again at 10:56 p.m.

* Tuesday May 12 at 9:47 p.m. from SW to NE. Another brilliant, overhead pass. Not to miss! A second fainter (but still bright) pass happens at 11:22 p.m. across the northern sky.

* Weds. May 13 at 10:13 p.m. and again at 11:49 p.m. across the northern sky.

Have fun following the astronauts' shiny chariot, and if you see any flares, let us know.

Posted by: rking@duluthnews.com on 5/9/2009 at 10:04 AM | Comments (0) | Permalink

Orange pajama moon

I watched the moon dissolve in a puddle last night as the wind disturbed the water's surface. When calm, you could make out the lunar seas and even a few craters (far left). Compare to the telescopic view below. All photos: Bob King

Last night was windy but clear and the moon was a cow's eye above the greeny trees. Tonight at 11:01 p.m. Central time the moon will reach full phase. May's full moon is called, appropriately enough, the Flower Moon. In our region, showy marsh marigolds will be exploding into bloom any day now. Many more flowers are just on the verge.

Your calendar may list the full moon date as Saturday the 9th. If so, its creator used Eastern time -- an hour ahead of Central -- which places the moment of fullness at 12:01 a.m. One thing you'll notice is how much lower in the sky tonight's full moon is compared to those in winter. In December and January, the highest point along the moon's monthly path coincides with full moon. Shining above the snowy landscape, those moons threw so much light I swear the air glowed. At the same time, the sun was at its lowest point in the sky, giving us very short days. Moon high, sun low.

The "almost" full moon last night photgraphed through a small telescope. The terminator, the boundary between day and night on the moon, is at far left. The small bright spot to the right of the terminator is the crater Aristarchus, while the equally bright crater Tycho stands out at the bottom of the moon. Both are visible in binoculars. Details: f/14 at 1/125" at ISO 100.

Things start to reverse in May. The sun is sprinting its way to the June 21 summer solstice, when it will reach its highest point in the sky for the year. Did you know the sun's just as high at noon today as it is during the first week of August? Since the moon follows the same path as the sun, and a full moon is directly opposite the sun, that must mean that as the sun climbs, the full moon descends. Sun high, moon low.

Tonight you'll find the moon in Libra the Scales rising around sunset. Even by 1 a.m. tomorrow morning, when at its highest elevation, the moon will only be about two outstretched fists above the southern horizon. Compare that to December when it's closer to seven fists high!

This map shows the sky at 10 o'clock Friday night. The full Flower Moon will be in zodiac constellation Libra. Created with Stellarium.

This seesaw act between sun and moon makes full moon watching a different experience every month. One consequence of the moon's low-riding is how long it stays orange. When we direct our gaze toward the horizon, we're peering through the bottom of our atmosphere where the air density (dust and water vapor too) is thickest. Denser air there scatters away the blue light of the moon turning it into an orange orb around the time of rising and setting. Since summer full moons spend much more time low in the sky than high, it takes a long time for the moon to shed its orange pajamas before dressing up in late night white.

Posted by: rking@duluthnews.com on 5/8/2009 at 11:43 AM | Comments (0) | Permalink

When I get old, just wheel me around the sky

My trusty plastic planisphere has seen many years of use. Photos by Bob King

Computer sky charting programs are wonderful. With a few keystrokes you can display the night sky for your location at any time past, present and future. I use a program to create many of the charts and maps in this blog. There are occasions however when the old analog "star wheel" or planisphere is a useful resource too. Sometimes it just feels good to hold a physical object and manually spin the dials without the need to be plugged in. Before the computer, I used one all the time to plan my observing sessions.

If you don't already own a planisphere, you may have seen them in science sections in bookstores. They're usually a flat disk or square with stars in the middle and a dial around the outside. A planisphere is mankind's attempt to crush the three-dimensional sky dome into a manageable two-dimensional map.

This detail shot shows the planisphere dialed in for 10 p.m. tonight May 7. One hour was subtracted for daylight saving time.

Planispheres consist of two adjustable disks held together by a metal pivot. You turn one disk against the other to show the sky for any time and date of the year. The oval window shows you the constellations visible at that time. It's that simple.

Oh, there are a few things to keep in mind when using a planisphere. First of all, you have to know your directions. Easy enough. If you face the sunset direction and flop out your right arm, it'll point north. Your left arm points south and your back is to the east. The center of the oval represents the point that's directly over your head, called the zenith, while the outer edge of the oval is the horizon. That metal pivot sits right over the North Star, which is as high above the horizon as your latitude.

Another consideration is daylight saving time. All planispheres are set for standard time; from March to early November, most of the country sets their clocks ahead to daylight time. Let's say you're out at 10 p.m. tonight. To set your wheel correctly, subtract one hour and align 9 p.m. with May 7 for an accurate view of the sky.

This is a view of the northern sky at 10 tonight with the planisphere. The yellow border of the oval represents the horizon. The closer a constellation is to the border, the lower in the sky it will appear. The pivot holding the two dials together is the North Star.

Now you're ready to find constellations on your own. Face north and turn the whole planisphere so the northern horizon runs along the bottom of the oval. You'll see the Big Dipper is way up high over the North Star. Now turn your planisphere to the opposite or southern sky (southern horizon at the bottom) and you'll see Leo and Virgo halfway between the horizon and the zenith. Higher up and to the left is the bright pink star Arcturus. By the way, the bigger the dot, the brighter the star.

To see the southern sky, you face south and then turn the whole planisphere so south is at the bottom of the oval. Leo is high up in the south-southwestern sky while Corvus is near the horizon.

You can also rotate the planisphere a quarter turn to the west and east. Just remember to face the direction you want to explore and then turn the whole planisphere so that direction is at the bottom of the oval where your thumbs would be.

How about a star wheel for folks living near the equator? I bought one of these when my wife and I were in Bogota, Columbia for the adoption of our children. The horizon runs straight across the middle and this picture shows the view looking north. To see the southern sky, you flip it over.

A closeup of the northern sky from Bogota's location near the equator. Notice that the pivot (North Star) is sitting right on the horizon, not halfway up in the northern sky as seen from much of the U.S.

I've seen star wheels for sale at local bookstores but if you'd like to look online first, check out two of the more popular ones here and here. They come in different versions for different latitudes. If you're in the northern U.S. or Canada, make sure you buy one good for 45-50 degrees latitude. Skywatchers in the central U.S. should use the 40-degree version while in the south, 30-35 is ideal. When you're outside at night, be sure to use either a dim flashlight or cover a regular flashlight with something red to preserve your night vision.

One day when the world ends and all the power trickles away, you and I will still be smiling at the night sky, planispheres in hand.

Posted by: rking@duluthnews.com on 5/7/2009 at 11:51 AM | Comments (0) | Permalink

Were the moon landings a hoax? Don't even ask!

Tonight watch for the moon to pair up with the bright star Spica in Virgo the Virgin. Like Regulus in Leo, Spica lies very close to the moon's path along the zodiac, which guarantees a regular monthly visit. This map shows the sky around 10 o'clock. Created with Stellarium.


Apollo 15 landed next to Hadley Rill in the summer of 1971. One of the mission's objectives was to sample rocks from both the rill area and the nearby Apennines Mountains (to the right). Lava carved the winding channel. Credit: NASA

I was looking up information on Hadley Rill the other evening and got angry. Rills are valleys on the moon formed in a couple different ways, either through crustal movements or carved by flowing lava. Hadley Rill is an 84-mile-long curvy river-like channel cut by repeated lava flows nearly four billion years ago when the moon was much more volcanically active. The rill is about a mile wide and visible in a 4-inch or larger telescope. Look for a delicate curlicue tucked along the edge of the Apennine Mountains on the "shore" of the Sea of Showers (Mare Imbrium).

A wonderful overview of Hadley Rill at the Apollo landing site taken by the Japanese Kaguya spacecraft currently orbiting the moon. The rill is about 1200 feet deep and extends 84 miles. Although not shown in this photo, the spacecraft also recorded the halo of the rocket exhaust left by the lunar module after it departed the moon. Credit: JAXA/SELENE

Apollo 15 astronauts James Irwin and David Scott landed near the rill on July 30, 1971 and spent the next three days exploring the area on foot and with the Lunar Rover. They drove right up to the edge of the rill and described the boulders that had tumbled from its walls, and took pictures of the multiple lava flows exposed in the ancient valley.

OK, so what's to get mad about?

Just try searching Hadley Rill on Google as I did while gathering material for this blog. Most of the hits are for videos purporting that the mission was a hoax. Almost no factual information about the rill is available unless you dig into the Apollo 15 mission archives at NASA or search additional astronomy sites. Like spammers, the moon-landings-were-a-hoax crowd has found the Internet a perfect place to disseminate misinformation.

Houston, we have a problem here.

This photo, taken looking across the rill by the astronauts, shows how the lava cut down through the moon's surface to reveal layers of lava flows from the past. Credit: NASA

I've listened to Apollo astronauts describe their experiences training for, landing on and exploring the moon. Thousands of men and women were responsible for making the Apollo missions a success. Are they all keeping quiet? Remember too that the Russians watched America's space activities very closely at the time. They would have loved to claim it was all a hoax. But they didn't. Pieces of over 842 lbs. of moon rocks gathered by the 12 astronauts over six missions have been distributed to scientists around the planet. Thousands of papers have been published about their makeup and origins.

Astronaut David Scott tends to the Lunar Rover while perched along the edge of Hadley Rill. Credit: NASA

Many find it offensive that a group of people would seek to gain notoriety and money by tearing down the achievements of others. Yes, we humans are imperfect creatures but it's crass and wrong to build your reputation on denigrating the efforts of others. Even when given clear, factual explanations for supposed "anomalies" found in mission photographs or videos, most hoax proponents refuse to acknowledge they might be mistaken. Hey, just because I was born in the last half of the 20th century and wasn't there to experience the founding of the United States in 1776 doesn't mean it didn't happen.

If someone tells you they heard the landings were all faked, just direct them to the BadAstronomy website. From there you or they can access additional links that will set the matter straight. For an excellent book on the moon that incorporates what we learned from Apollo, I highly recommend Charles Wood's The Modern Moon: A Personal View. It's ideal for armchair as well as amateur astronomers.

It's all about good information and learning how to find it. Sometimes you have to dig through the garbage but it's there. Discerning the real from the bogus is a lifelong occupation.

Hadley Rill is shown in a wider context in this picture of the moon taken through an amateur telescope. Credit: Frank Barrett

Posted by: rking@duluthnews.com on 5/6/2009 at 1:31 PM | Comments (5) | Permalink

Planet #344 please step forward

This artist view shows the star Gliese 581 (at right) and three of its planets. Researchers recently announced the discovery of a 4th planet in the system. The current number of extrasolar planets now stands at 347; the new planet is #344 on the list. Read more in the Extrasolar Planets Encyclopedia. Credit: ESO

The discovery of the lightest planet beyond our solar system was announced by Swiss exoplanet researcher Michel Mayor two weeks ago. Called Gliese (GLEE-zuh) 581e, it orbits the red dwarf star Gliese 581, 20 light years away in the zodiac constellation of Libra the Scales. The star isn't visible to the naked eye but a small telescope will show it.

The new orb weighs in at 1.9 Earths and likely is a rocky sphere like our planet. Mayor made the discovery after four years of observations using the 3.6 meter (140 inch) European Southern Observatory telescope in Chile equipped with a special instrument called a spectrograph.

An exoplanet exerts a tug on its host star during its orbit, causing the star to whip around in a tiny circle. The red wiggle represents light from the star as it recedes from Earth; the blue is light as it approaches Earth. The difference in speed tells astronomers much about what's doing the tugging. Credit: ESO

One of the main ways of finding exoplanets is by measuring the gentle tugs planets place on the stars they orbit. As a planet revolves around its host star, its gravity pulls the star first one way and then the other in a rhythmic pattern. A spectrograph measures the very slight change in the star's speed. From this astronomers can determine the planet's mass and details of its orbit.

Gliese 581 was already known to possess three planets, discovered by Mayor and other researchers in the past few years. Known as Gliese b, c and d, they range from five to 15 times more massive than Earth.

Planetary scientists are on a quest to find smaller and smaller planets in hopes of discovering another Earth in a habitable zone -- neither too cold nor too hot -- near its host star. At just under two Earths, Gliese 581e comes close. Unfortunately it's probably not the planet we're looking for. It orbits so close to its host star the heat has probably cooked away the atmosphere and baked the surface. Just the same, scientists headed in the right direction. It's only a matter of time before our sensors detect the familiar signatures of oxygen and methane on some distant world.

The Eta Aquarids appear to radiate from the constellation Aquarius, just rising in the morning sky in May. To watch for meteors, find a comfortable chair and face east just before dawn. This is an iffy shower for northerners but it may reward the ardent observer the pleasure of seeing bits of Halley's Comet flash across the sky. Created with Stellarium.

Tomorrow morning is the peak of the Eta (EH-tuh) Aquarid (uh-KWAR-id) meteor shower. The shower is a good one for observers in the tropics and southern hemisphere, where the meteor radiant point is high in the sky. Skywatchers there will see up to 85 "shooting stars" per hour. For the U.S., Canada and Europe, it's a minor shower with maybe 20 meteors visible per hour from a dark sky just before dawn.

Eta Aquarids are actually bits of dust and ice from the tail of the most famous comet of all -- Halley's. Halley's Comet last swung by Earth in 1986. Every time it passes it leaves a trail of debris like Pigpen in the Peanuts cartoon. Earth passes through the trail twice a year. The first crossing gives us the Eta Aquarids; the second the Orionid meteor shower in October.

Eta Aquarids are fast and known for leaving bright, lasting streaks in their wakes. I'd set the alarm in the off chance of catching one, but the forecast for our region calls for rain. I hope your weather is better.

Posted by: rking@duluthnews.com on 5/5/2009 at 1:16 PM | Comments (0) | Permalink

Fire, flare and moonlight

Sparks from a backyard bonfire rise toward the moon last night. Details: 17mm at f/5.6, 4-second exposure at ISO 400. All photos: Bob King

The day was so fine yesterday a celebration was called for, so I got a bonfire going in the backyard at nightfall. The moon was up near Saturn and added its cool silver light to the warm oranges of the flames. Fire seems a fitting end to the day, a chance to sit down, recollect and rest my bones.

Last night's 9-day-old moon photographed through a small telescope. Copernicus, mostly filled with shadow at the time, is midway along the moon's left edge. Details: 1/60" at f/14, ISO 100.

In yesterday's blog I talked about the crater Copernicus, and I must say it didn't disappoint last night. Situated in a large dark plain and lit in vivid contrasts of light and shadow by the rising sun, the crater stood out so distinctly and with such force I could see it with my naked eye. Binoculars showed its bright rim and shadow-filled interior. Once I got the telescope pointed at the moon, Copernicus put me in a sort of Vulcan mind-meld. I was simply powerless to look elsewhere. The puckered and wrinkled terrain surrounding the crater recalled the wrinkles and folds around an old man's eyes.

As the temperature dropped into the 30s, I appreciated the fire even more. A little moongazing followed by firegazing proved the ideal combination of study and relaxation. At 10:45 p.m., the Iridium 75 satellite flared in the northeastern sky near the bright star Vega.

I never get over the thrill of seeing an Iridium flare. The satellite first makes its appearance as a faint, moving star that slowly brightens and then suddenly becomes MUCH brighter. Last night's flare equaled Venus in intensity! 10 seconds later the satellite faded away like a tiny ember.

Looks like a meteor, doesn't it? It's the Iridium 75 satellite flaring near Vega (the bright star at right) last night at 10:45 p.m. The satellite moved from left to right during the 30-second time exposure. It started out dim, brightened outrageously in the middle and then faded away.

We touched on the Iridium telecommunications satellites several times before in this blog. Approximately 66 of them orbit 480 miles above the Earth and provide satellite phone and paging services to subscribers. As they pass over a region, the satellites' large, shiny antennas catch the sun briefly and send a brilliant reflection your way called a flare. Watching Iridium flares is a fun pasttime. Some are modest but just as many are as bright or brighter than Venus. A flare usually lasts just a few seconds and the satellite then fades back to invisibility. For more on flares, check out this great resource.

Here are a few over the coming nights visible from Northeast Minnesota. Times are given to the second. Flares are brief so go outside a few minutes to get oriented.

* Iridium 42 on Tuesday May 4 at 11:25:55 p.m. Look two outstretched fists high in the west-southwest.
* Iridium 40 on Tuesday May 4 at 11:34:50 p.m. two fists high in the west-southwest.
* Iridium 72 on Weds. May 5 at 10:36:50 p.m. three fists high in the northeast.
* Iridium 62 on Thurs. May 6 at 10:30:47 p.m. three fists high in the northeast.
* Iridium 18 on Thurs. May 6 at 11:17:03 p.m. two fists high in the west-soutwest.
* Iridium 39 on Fri. May 7 at 11:11:07 p.m. two fists high in the west-southwest.
* Iridium 80 on Fri. May 7 at 11:20:06 p.m. two fists high in the west-soutwest.

Flares are particular to a region. To find when and where they occur for where you live, go to the Heavens Above website, log on and provide your location, then click on "Iridium Flares" under the "Satellites" heading. With summer coming, you may not need a fire on hand to keep you warm but make one anyway if you can. Few things are better for the soul.

Posted by: rking@duluthnews.com on 5/4/2009 at 12:48 PM | Comments (0) | Permalink

Amazing photos reveal the nature of Saturn's rings

Venus and Jupiter Sunday morning just before 5 a.m. The two are about five outstretched fists apart. Photo: Bob King

Two morning lights against a clean blue sky. At dawn today I listened to the first white-throated sparrows and robins lay out a carpet of song for the sun's arrival. By 5 o'clock all the stars except Venus and Jupiter were lost in a bright sky. Jupiter was an easy catch in the southeast while Venus required a walk to the backyard to extricate it from the tangle of trees near the eastern horizon. Have you ever gone into your yard at an odd hour of the night? The space always feels weird to me -- strangely vacant yet full of possibility as if imaginary animals might jump out at any moment.

The moon at nine days. Besides the mountain ranges, Tycho and especially Copernicus should be visible in ordinary binoculars. Plato and Langrenus are a bit more challenging. Saturn is visible about "three fingers" above the moon Sunday night. Photo: Frank Barrett

Tonight looks clear for our region, an ideal time for some moonwatching. The eight and nine-day-old moons are probably the best for spying craters along the terminator, the curved edge that defines the advancing line of sunrise on the moon. Even a magnification of 7x will reveal rough textures there, and if you can brace yourself so as not to jiggle the binoculars, you'll be able to make out the circular outlines of the bigger craters. See if you can find two of the moon's grandest -- Copernicus and Tycho, which span 58 and 53 miles across respectively.

This photo made by Cassini shows the long, narrow shadow of Mimas and a line of tiny shadows along the inner edge of Saturn's B ring. Credit: NASA / JPL / SSI

In this closeup, you can better see the line of shadows cast by clumps of ice boulders that are concentrated along the B ring's edge. See the full view here. Credit: NASA / JPL / SSI

I was digging around online the other day and came across a photo that hinted at something I've always wanted to see. Take a look at the two images taken by the Cassini spacecraft still in orbit around Saturn. The wide field picture shows the shadow of the moon Mimas crossing a part of Saturn's ring system. Since the rings are nearly edge-on to the sun and Earth, the innermost moons as well as any large chunks within the rings cast long shadows. Look more closely and you'll notice an arc of long, jagged shadows just within the edge of the bright, white band called the B ring. They look like a tiny mountain range.

Cassini took this picture directly above the B ring. Now you can see the actual clumpiness within the ring's outer edge. Credit: NASA / JPL / SSI

Saturn's rings are made of millions of individual icy boulders that are below the resolution limit of any telescope on Earth. Even Cassini can't see them, and I was so hoping we'd be able to image this. Yet these photos are very exciting because they likely represent the shadows of ring particles that form clumps within the B ring. Since sunlight is coming in at such a low angle, even small things can cast large shadows as we touched on in this earlier blog. The clumps form through their own self-gravity and are always on the move, exchanging boulders with other clumps as they revolve around the planet.

2007 artist impression of clumping boulders and particles within Saturn's rings. The largest ones are a few meters across. Credit: Image courtesy NASA/JPL/University of Colorado

Scientists believe the clumps form in the B ring because the moon Mimas periodically compresses the material there as it orbits Saturn. How cool is that!

Posted by: rking@duluthnews.com on 5/3/2009 at 11:36 AM | Comments (0) | Permalink

Round and round the heavenly highway

Artist Gary Meader at the Duluth News Tribune created this in his free time just for fun. It's very well done and gave me a good laugh. I hope you enjoy it too.

Friday night's moon photographed through a small telescope.
Three lunar mountain ranges are marked -- all of them named
after their European counterparts. Details: 1300mm at f/14, 1/125"
at ISO 400. Photo: Bob King

We had a few breaks in the clouds last night, enough for a moonlit walk and then some time behind the eyepiece. The moon was at first quarter phase or seven days old. Hundreds of craters stood out crisply in the low sun and the jaggedy peaks of the Alps and Apennines mountain ranges were breathtaking. I was still able to trace the full lunar disk in Earthshine through the scope at low power. Any other Earthshine seekers still watching for this ghostly glow?

Tonight the moon will be just below Leo's brightest star Regulus. You may have noticed that the moon visits the star once a month. Regulus just happens to lie along the ecliptic (ee-CLIP-tic), the name given to the path the moon, sun and planets take through the sky. As the moon cycles through the entire zodiac in a month's time, it passes near Regulus and any planets along the way. Tomorrow it'll sidle up by Saturn.

Watch for the moon near Regulus tonight (Saturday) when the sky gets dark. All the planets, sun and moon travel along an imaginary circle in the sky called the ecliptic, which represents the flat plane of the solar system. The ecliptic changes height in the sky from season to season because of the tip of Earth's axis. Created with Stellarium.

The moon's orbit is inclined to the ecliptic, so it typically rides a bit above or below that path. However every few years the moon crosses right in front of Regulus, occulting it from view for a short time. Two other bright zodiac stars, Spica and Antares, are also close enough to the ecliptic to be occulted. This coming June, Antares in Scorpius will become the moon's next victim.

Our solar system is almost flat, like a plane with the sun at its center. The eight planets race around the sun like runners on a racetrack. Project that flat plane into the sky from our perspective here on Earth and that's the ecliptic. If you could hover above the solar system and look down on all the planets, you'd see all their nearly circular orbits laid out like nested hula hoops.

The orbits of the planets resemble runners on a flat racetrack. The tipped circle in the background is Pluto, recently reclassified as a dwarf planet. Credit: ESO

Earth runs the racetrack with all the other planets. As we look to our left and right, we see them passing one another all going the same direction but at different speeds. In a real race, no one is guaranteed a particular time, but in a planet race, each planet orbits the sun with a fixed period. Mercury is always in first place with a time of 88 days since it revolves fastest, while Neptune comes in dead last at 165 years!

Not only does the moon cover up stars during its monthly swing through the zodiac but planets cover other planets and stars that lie along the ecliptic. Since planets appear so much smaller than the moon, planetary occultations are very rare. Venus will blank out Regulus on October 1, 2044 and Jupiter on November 22, 2065. Guess I won't be around for those but I hope some of you will. To give you an idea of how unique planet occultations are, the last time Venus and Jupiter overlapped was in 1818. Want to know more about the future sky? Check out The Ultimate Almanac.

Every few years the movements of the planets conspire to create what appear to us as interplanetary traffic jams. That should be no surprise since their paths nearly overlap as seen from our edge-on, in-the-plane view of the solar system. Mercury, Venus, Mars and Jupiter will all huddle together in the morning sky on May 16, 2011.

I'm planning on being around for that one.

Posted by: rking@duluthnews.com on 5/2/2009 at 12:17 PM | Comments (4) | Permalink

Rembrandt meets Mercury

A self-portrait of the artist Rembrandt Harmenszoon van Rijn (left), and his crater namesake on the planet Mercury. For a detailed closeup of the crater, click here. Crater credit: NASA/Johns Hopkins University Applied Physics Laboratory/Smithsonian Institution/Carnegie Institution of Washington.

I imagine that Rembrandt would have been surprised to learn that a 430-mile diameter crater on Mercury was recently named after him. The well-known painter lived during the mid-17th century, at the time of the invention of the telescope. By the late 1600s, we no longer looked at planets as dots of eternal luminescence but actual physical worlds like the Earth.

Mercury had been known since antiquity. Rembrandt may have even seen it himself during his lifetime. Then is was little more than a "star" that followed the sun in morning and evening twilight. Today we know the little planet as a 3000-mile-diameter, crater-pocked sphere that orbits close enough to the sun to get seared to 800 degrees during its 88-day-long day. Since Mercury's atmosphere is so rarefied, it can't hold onto that heat. At night the temperature plummets over 1000 degrees to 270 below zero.

The Rembrandt impact basin is so big it would stretch from Washington D.C. and Boston. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Smithsonian Institution/Carnegie Institution of Washington

NASA just announced the discovery of a huge, new impact basin (large crater) never seen before on the planet. Named after Rembrandt, it was photographed by the Messenger spacecraft during its October 2008 flyby of the planet.

According to convention, Mercury's craters are named after deceased artists, musicians and authors. Rembrandt shares the planet with other notables like Beethoven, Andre Kertesz (one of my favorite photographers) and the Chilean poet Pablo Neruda.

Rembrandt is special not only for its size but also because it's so deep that scientists can see down into Mercury's crust to the actual time the crater formed some 3.9 billion years ago. Normally such huge impacts release large floods of lava that cover over the scar. While Rembrandt has its share of lava, but other parts of the basin are as fresh as the day they formed. When Messenger finally moves into orbit around the planet in March 2011 for closeup study, we'll learn more about what Mercury was like eons ago.

Mercury as photographed by the Messenger spacecraft during its most recent flyby in October 2008. The craft will zoom past the planet again this September before settling into orbit in 2011. Credit: NASA

That wasn't the only discovery. Like Earth, Mercury's surrounded by a magnetic bubble, called a magnetosphere, created by churning currents within its iron core. Our magnetosphere shields us from much of the sun's dangerous radiation. Scientists were surprised to discover that Mercury's bubble was ten times more dynamic and changeable as our own.

Finally it turns out that Mercury has magnesium, calcium and sodium in its vanishingly thin atmosphere. If you're thinking that these are odd things to find in air, you're right. They were liberated from the surface by fierce solar radiation and ongoing meteorite hits. If once Mercury once had a thicker atmosphere, it lost it long ago because its gravity was too weak to hold onto its air.

Mercury is still in our evening sky near the Seven Sisters cluster (Pleiades). It's fainter than it was a week ago but worth the effort to see. Bring binoculars for assistance. This map shows the sky looking northwest above the sunset point about 40 minutes after sunset (around 9 p.m. for N. Minn / NW Wisc) In a week the planet will disappear into  bright twilight. Created with Stellarium.

We've come a long way since the time of Rembrandt in our understanding of the uniqueness of each planet, moon, comet and asteroid in our solar system. I trust the great Dutch artist would nod in appreciation. Artists and scientists share the same motivation after all -- to reach beyond the known in search of a new perspective.

Posted by: rking@duluthnews.com on 5/1/2009 at 1:33 PM | Comments (0) | Permalink

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