Side by side, these giants stalk the night

Posted on September 2, 2010 by astrobob

Jupiter (left) photographed by Anthony Wesley and by the Hubble scope (right). Larger version of the Hubble image. Credit: Anthony Wesley, NASA/ESA

The name of Anthony Wesley, an amateur astronomer from Australia, often comes up in this blog because of his remarkable discoveries of two meteoroid impacts on Jupiter over the past two years. He also takes some of the best pictures of the planet. One of his most recent, made on August 30, when the atmosphere was exceptionally calm, show details that compare well with images made by the Hubble Space Telescope.

It’s rare when the air is calm at both ground level and high up in the atmosphere. To see fine details on a planet, you need high magnification. On most nights, even the seemingly serene ones, the air higher up is roiling and shifting about enough to degrade telescopic images. Everything looks OK at low power, but jump up to 150x – 200x for a better look, and you’ll often discover your image turns to mush. You’re not just magnifying the object, you’ll also magnifying turbulence a couple hundred times. On unsteady nights, planets and stars range from looking a little fuzzy to fluttering around like clothes on a laundry line. I’m not kidding – it can get that bad.

Wesley was granted a rare window of calm and took advantage of it by making a beautiful photograph, certainly one of the best ever taken by an amateur. Having experienced a few serene and steady nights in my life, I can imagine the impression Jupiter must have made. With no flutter, planets and the moon look like the real things, not images – you literally feel like you’ve left the Earth and are now OUT THERE. Details you never imagined you’d see in your lifetime are staring you right in your face. Disbelief is a common feeling shared by many amateur astronomers during these infrequent and splendid moments.

It's surprisingly easy to find Uranus with binoculars. Point them at Jupiter and then look to the planet's upper right. Uranus is the same brightness as the star directly above it. The dates show Jupiter's changing position over the next two weeks. The circle is about 3-4 degrees across and represents the view through binoculars around 11 p.m. Created with Stellarium

Yesterday we looked at Jupiter and how you could use the planet to guide you to the constellation Pegasus and the Great Square asterism. Over the next couple weeks, we can use it again to find the planet Uranus. Some of you may recall that Jupiter was near fainter Neptune last year when the pair was in Capricornus the Sea Goat. Jupiter, closer to the sun than Neptune and moving more quickly in its orbit, has traveled on, leaving the 8th planet to fend for itself. Jupiter’s new companion is Uranus, another one of our solar system’s large, gaseous planets similar in many ways to Neptune.

Earth and Uranus are very different planets in size, temperature and in the tip of their axes. Credit: NASA

Uranus was discovered by William Herschel in 1781 from his backyard garden in England. At the time he interpreted the tiny disk he saw as a comet. Not long after, astronomers determined it was a planet, the first new one identified since antiquity. Uranus is four times the size of Earth, orbits 1.8 billion miles from the sun and is swaddled in a thick atmosphere of mostly hydrogen and helium where the winds can blow up to 560 mph. Check out that robin’s egg blue color. It’s caused by methane gas which absorbs the red light from sunlight and reflects the blue back.

Like Jupiter, Saturn and Neptune, Uranus has no surface to stand on. Beneath the atmosphere, the planet’s interior is filled with a mush of slushy water and ammonia ices. One of the planet’s most delightful peculiarities is the tip of its axis. Our planet’s tip is 23.5 degrees, enough to give us the joy of four seasons, but Uranus is tipped 98 degrees, meaning it axis is nearly parallel with its orbit. The dang planet is spinning sideways with its polar axes sticking out left and right and equator belly up. Scientists suspect a large impact long ago may have knocked it out of kilter.

Uranus's axis is so highly tilted, the poles are left and right rather than at top and bottom. This photo also shows the planet's faint ring system. Credit: NASA/ESA

Since Uranus is 6th magnitude or comparable to the faintest stars visible from a dark sky, only the keenest-eyed will see it without optical aid. Thankfully, it’s plenty bright and easy to see in binoculars. Use the map above to find it, and if you keep watch in the next few weeks, you’ll see the whirrings of the solar system as faster-moving Jupiter passes right under the other blue planet. While you’re taking in the scene, don’t forget to watch for the nightly “moon ballet” of Jupiter’s four brightest satellites.

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Go fly a horse

Posted on September 1, 2010 by astrobob

The last quarter moon photographed this morning through a 10-inch telescope. Much of the expansive dark grey region to the upper right is a vast lava plain called Oceanus Procellarum or the Ocean of Storms. The bright, bullseye-like crater ringed with rays right of center is Copernicus. Credit: John Chumack

The last quarter moon was beautiful this morning. I was out with the dog at 7 a.m., looked up and there it was nearly at the top of the sky. I was tempted to take out the telescope but had to move on to other things. Scope owners – even binocular users – who are up in the early morning after sunrise can make the moon their target. As you can see from the photo, the craters at this phase are magnificent. They make a sweet contrast to the large, dark lunar seas.

This map shows the sky as you look east around 10:30 p.m. in early September. One outstretched fist is equal to about 10 degrees of sky. The Great Square is about two fists on a side. Maps created with Stellarium

Pegasus represents a winged, flying horse. You'll sometimes see him pop up in various forms in movies like Harry Potter or Clash of the Titans.

We begin a new month today with numerous astronomical highlights not the least of which is Jupiter. The giant planet will be its closest to Earth in 47 years and the apple of many a sky watcher’s eye. Jupiter comes up in the east around 9 p.m. and is easily visible by 10:30. It’s that hugely bright star you simply can’t miss. Once found, you can use the planet to locate the flying horse constellation, Pegasus. Look two fists above and to the left of Jupiter to trace out the Great Square, a nifty figure hard to miss. Once you’ve nailed the square’s four corner stars, connect the dots to the horse’s legs (upper right corner of the Square) and its long neck and head which begin at the square’s lower right corner and reach all the way to the star Enif. By the way, this horse is flying upside down. No matter, there is no up or down in outer space.

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Researcher finds new meteor crater without leaving home

Posted on August 31, 2010 by astrobob

The newly discovered Gebel Kamil crater in southern Egypt is a little wider than a football field and still relatively fresh. Credit: Landsat image from Google Earth

Imagine scanning through images in Google Earth and stumbling across a meteor crater made by a hunk of flying iron from the asteroid belt. That’s just what Vincenzo de Michele, former curator of the Natural History Museum in Milan, Italy did while scouring satellite photos in search of new impact craters. Not long after, in February 2009, he and others undertook an expedition to the site in southern Egypt near the Sudanese border to verify whether it was a true crater.

Oh yes indeed it was.

They found thousands of fragments of nickel-iron meteorites scattered in and around the Kamil Crater, a modest hole in the ground 184 feet across and 52 feet deep. What’s amazing is how fresh the crater is – check out those rays of colorful rock spray still visible beyond the crater’s rim. Scientists estimate the original meteorite was about 5 feet across, weighed 10 tons and fell some 5000 years ago.

The largest Gebel Kamil meteorite found so far - a 183 lb. thumbprinted beauty. Credit: Univ. of Siena / Museo Nazionale dell'Antartide, courtesy Dr. Luigi Folco

This past February, a combined Italian-Egyptian geophysical expedition made a careful survey of Kamil Crater and recovered 5,178 meteorite fragments – plus impact-related glasses – totaling 1.7 tons! The largest fragment weighs 183 lbs. (83 kg) and its surface is covered with beautiful regmaglypts or “thumbprints” created when the fierce heat of atmospheric entry melted softer spots which sloughed off during flight. Most of the meteorites have torn and ripped shapes indicating that the original mass likely exploded during flight due to a good pounding by the atmosphere.

The Kamil crater is 184 feet across with an upraised rim of blasted rock about 10 feet high. The interior is partially filled with sand. Credit: Univ. of Siena / Museo Nazionale dell'Antartide, courtesy Dr. Luigi Folco

The meteorite, now known as Gebel Kamil, after a distinctive spire of rock in the area, is different from many iron meteorites because it contains an unusually large amount of nickel. Most irons contain between 5-10% nickel but Gebel Kamil is loaded with 20%. This makes it a considerably rarer type of iron meteorite called an ataxite. The irons from Meteor Crater east of Flagstaff, Arizona are of a more common variety containing less nickel.

A typical Gebel Kamil meteorite (left) looks like a grenade or bomb fragment (shrapnel). The photo of the slice at right shows additional minerals inside and an interesting stress pattern in the metal. Photos: Bob King

So you can experience a little of the adventure yourself in finding a meteorite crater, this link will bring you to Google Earth where you can explore the Kamil crater and vicinity from your very own desktop. Lots more photos posted by the February expedition team are HERE.

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The sisters of fall meet the waning moon

Posted on August 30, 2010 by astrobob

The moon, Aries, the Pleiades and the Hyades are splayed across the eastern sky around 1 a.m. tomorrow morning. Created with Stellarium

Tomorrow morning the last quarter moon will be near the Seven Sisters star cluster also known as the Pleiades (PLEE-uh-deez). This true star cluster has a shape like a small dipper and is sometimes confused for the real Little Dipper constellation. The Pleiades are 440 light years from Earth and comprise a gravitationally-bound cluster of some 500 stars. With the naked eye you’ll see six or seven stars huddled closely together like friends around a fire, binoculars show dozens and telescopes far more. The nearness of the moon will help you find the cluster, but its light will compromise the view. Try binoculars to see them best.

The Pleiades is a young star cluster with many hot, blue-white stars. Its compact form makes it the most obvious cluster visible with the naked eye. The blue mist is a cloud of fine interstellar dust the cluster passing through. Starlight illuminates the dust by reflection. Credit: NASA, ESA, AURA/Caltech, Palomar Observatory

Above the moon, you’ll easily spot one of the smaller constellations, Aries the Ram, comprised of three stars arranged like a bent index finger. Below the Seven Sisters is yet another star cluster, the Hyades (HYE-uh-deez). It’s takes up a bigger piece of the sky in part because at 150 light years distant, it’s considerably closer than its sister cluster. The bright star Aldebaran is closer yet but happens to be in the same line of the sight as the Hyades; it’s not a true cluster member.

The Hyades were sisters to Hyas, the son of the Greek god Atlas. When Hyas was killed by a wild boar, the sisters were so saddened they died of grief. Zeus took pity upon them and placed them in the heavens in the constellation of Taurus the Bull. The Hyades were half-sisters to the Pleiades, who were also daughters of Atlas.  Atlas was the dude who was forced to carry the heavens on his shoulders. One version of the Pleiades  story recounts that Orion pursued the young ladies because Atlas was too preoccupied with his celestial weightlifting. To ease Atlas’ concerns about Orion’s intentions, Zeus turned the daughters into stars and floated them up to the sky.

Statue of Atlas carrying the heavens on his back. Credit: Luis Miguel Bugallo Sánchez

In late August, both star clusters only begin to nudge into the night sky – you have to stay up late to catch them. By fall, they rise during the evening hours and presage the arrival of the winter constellations Taurus, Orion and Gemini.

If you’re more of an early evening sky watcher and would rather wait for fall for the Pleiades to come to you, no problem. We’ve got some sleep-saving viewing times for the International Space Station (ISS) through the remainder of the week.

All passes listed below will happen in the northern sky with the space station moving from northwest to northeast. The times are Central Daylight and good for the Duluth region. For times for your town, please click HERE and key in your zip code.

* Tonight starting at 9:11 p.m.
* Tues. Aug. 31 at 8:02 p.m. and again at 9:38 p.m. The second pass will be short. Watch for the ISS to turn red through binoculars as it enters Earth’s shadow.
* Weds. Sept. 1 at 8:30 p.m.
* Thurs. Sept. 2 at 8:58 p.m.
* Fri. Sept. 3 at 9:25 p.m.
* Sat. Sept. 4 at 8:17 p.m. and 9:52 p.m. Another opportunity to watch the sun set on the station as it enters Earth’s shadow.

Tomorrow we’ll look at how a new impact crater – with meteorites – was discovered in southern Egypt by someone scanning Google Earth photos.

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First feeling, then understanding

Posted on August 29, 2010 by astrobob

Venus, Spica and Mars form a variety of different shaped triangles as they ply the twilight sky over the next few days. These maps show the view looking southwest a 1/2 hour to 45 minutes after sunset. Created with Stellarium

Mars continues to pester Venus in the west these late August evenings. It seems the two planets will never part. That’s good news for sky watchers who want to follow Mars as long as possible until it’s too close to the sun to see. Mars is much fainter than Venus – only a little brighter than the stars in the Big Dipper – but its proximity to a brighter planet will make it relatively easy to find for some time to come.

Don’t count on seeing this tiny orange spark by eye alone. You’ll need binoculars. Tonight through September 1, you can also watch Venus approach Virgo’s brightest star Spica. The two will be closest on Tuesday evening when they’re separated by just one degree. That’s the width of your little finger held against the sky. Since Mars is only 4 degrees from Venus, you’ll be able to watch the whole show at one time in the same field of view of your binoculars. That’s pretty neat.

Astro Bob, age 13, stands next to his shiny, new 6-inch telescope on a spring afternoon in 1967.

When I was just getting into astronomy around age 11, I kept a close watch on what the planets were doing. I drew maps and wrote elaborate descriptions of their current positions and where they were headed. One of the most confusing aspects of this crazy and wonderful hobby is the simple fact that nothing stands still in the sky. The Earth’s rotation, the individual movements of the planets and the moon’s revolution combine to throw everything into disarray. You think Mars is over here when it’s really over there. Why can’t everything stand still for a while so we can get better acquainted? I suppose that would be nice, but like B.B. King says, the thrill would be gone. The very motions themselves are what keeps things interesting. That’s why it’s not only fun but instructive to follow Venus and learn the constellations. Even if you don’t know every detail of what’s happening, you become familiar with celestial and planetary motions in a very intuitive way through the simple act of watching. Then next time you read why Mars sometimes moves backwards or why the stars rise four minutes earlier each night, you’ll have that “Aha!” moment when things snap into place. Whenever possible, it’s a good idea to begin with the visceral experience of something, however ignorant you are of its workings, before proceeding to an intellectual understanding of it.

The same idea applies when reading scientific material. If you read one level beyond your level of knowledge, the point where you only begin to grasp a concept, you sow the seeds in your mind for deeper understanding over time. I remember struggling over articles in Sky and Telescope magazine years ago, but read them anyway even if only a few sentences made sense. Now I find that almost all the articles are understandable. I guess it comes down to attempting more than you think you can do. Happy planet watching!

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Got 38 seconds? Good. We’re go for orbit

Posted on August 28, 2010 by astrobob

I was poking around on the Internet and stumbled across this time lapse video made by astronaut Don Pettit from the windows of the International Space Station sometime during his stay there from late November 2002 to May 2003. I’ve watched it again and again and am constantly amazed by what you can see. Things to watch for are the aurora borealis snaking along Earth’s circumference, stars rising in the black background of outer space, moonrise and moonlit clouds and the colorful edge of day at the video’s end.

Airglow seen from the ground. It's very, very faint but can be glimpsed as colorless streaks under the darkest skies. Credit: Space Physics Research Group, Univ. of California, Berkeley

Another curious sight in the video is a thin, orangey-green membrane of light enclosing the planet. This is the airglow or nightglow, a layer of air about 60 miles high where atoms of oxygen, nitrogen and sodium that were ionized by ultraviolet light from the sun during the day recombine at night and emit faint red and green rays of light. Solar UV has the power to knock electrons free from their comfortable orbits around atoms, but once the sun has set, the electrons return and recombine with those atoms, giving off little quanta or bundles of energy as they seek their original positions around the atomic nucleus. The process is called ionization because an atom without its usual complement of electrons is said to be ionized. In human terms, if you had a particularly difficult day at work, you might feel “ionized” by the end of the day. Coming home to a nice meal and glass of wine is equivalent to recombination.

The Big Bear Solar Observatory, located in Big Bear Lake in the San Bernadino Mountains in California uses its 63-inch (1.6m) telescope to study the sun in great detail. The lake creates a very stable atmosphere around the telescope allowing for some of the sharpest, most detailed images of the sun ever. This past week a new adaptive optics system was used on the mirror. Adaptive optics is a technique employed by astronomers to sidestep the blurring effects caused by the atmosphere. A special sensor monitors distortions in the air, sends that information to a computer when then adjusts the shape of the flexible mirror to correct for the distortion. Using adaptive optical systems, astronomers can take pictures nearly as sharp as those made by the Hubble Space Telescope which orbits above the atmosphere.

The most detailed picture of a sunspot ever obtained in visible light was seen by new telescope at NJIT's Big Bear Solar Observatory. Credit: Big Bear Solar Observatory

Using the new setup, the Big Bear folks resolved details on the sun’s surface as small as 50 miles – not bad considering it’s 93 million miles away.  Check out that picture – whew, talk about in your face! Sunspots are regions of strong magnetic activity on the sun’s surface or photosphere. They appear dark only because they’re several thousand degrees cooler than their surroundings.  This picture shows the classic sunspot structure of dark umbra encircled by the lighter penumbra. The numerous small cells are called granules. Each one is a similar to a air bubble rising in a pot of boiling water. Similar except for size. An average one is 600 miles across or about as big as Texas. They’re driven to the surface by heat from below. The bright part is rising solar gas – mostly hydrogen – while the dark borders are where the gas is sinking back into the sun after having cooled upon reaching the surface.  Is that cool or what?

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Venus proves that beauty can be elusive

Posted on August 27, 2010 by astrobob

Venus is the solitary light above the TV and radio towers in Duluth's "antennae farm" last night. Details: 200mm lens at f/2.8, 1/80-second exposure, ISO 800. Photo: Bob King

Heck, it’s the brightest planet, and about as far as it gets from the sun in the evening sky, so how come Venus is hiding in the sunset glow? Checking the stats, I see Venus reached its greatest eastern elongation of 46 degrees – largest distance east of the sun – only a week ago. That’s half the distance between the horizon and the overhead point. Shouldn’t the planet pop right out in the sky?

Nope. Instead, you’ll find Venus very low in the southwestern sky well to the left of the sunset point about a half hour after sunset. If you’re on a lake or standing in an open field, it’s easy to see, but for many of us who live around buildings and trees, it’s easily lost behind a roof line. This is sad, because we can’t fully appreciate how amazingly bright this planet is so long as it can’t step up to the plate.

Venus isn’t to blame. It has no choice but to follow the path all the planets must follow as they orbit the sun. Called the ecliptic, it’s an imaginary circle in the sky that closely defines the flat plane of the solar system. Since all the planets (and moon) orbit in or near this plane, we always see them following the same path through the same 12 zodiac constellations over the days, months and years. Even the sun tracks along the ecliptic as seen from Earth, because we’re driving on the same race track as the rest of the planets. Since we’re stuck on Earth and can’t see ourselves traveling along the ecliptic from afar, the sun appears to follow the ecliptic instead. Watching the sun’s seasonal travels up and down the sky is a reflection of our planet’s orbital motion around the sun. The sun’s not moving, we are.

The changing angle the ecliptic makes to the horizon strongly affects how easily planets are visible when near the sun. The left panel shows Venus tonight when its path follows a long angle to the horizon; the right panel depicts its next period of evening visibility in the spring of 2012, when it will be much higher. Created with Stellarium

This time of year, the ecliptic makes a very shallow slant to the evening horizon for sky watchers in mid-northern latitudes. Venus may be a long ways to the left of the sun, but because its path is at a very low angle, it never gets far from the horizon. That’s why we have to work a little more to find it.

Every couple years, Venus puts on an evening show in the early spring sky. The next time this happens is March 2012. During spring, the ecliptic cuts the horizon at a much steeper angle. While Venus will be the same angular distance from the sun then as it is tonight, the steep slant lofts the planet high into the sky where its brilliant beacon can be seen by all.

In a sense, Venus is a bellwether for where the sun is headed next. The sun reached its highest point in the sky (farthest north) for the northern hemisphere on the June 21st summer solstice. Since then it’s been dropping to the south and sinking lower in the sky every day as we approach fall. Notice that Venus is to the east of or ahead of the sun. Where the planet is now is where the sun will be in late September as its heads southward to its lowest point in the sky called the winter solstice. In spring, Venus presages the sun’s ongoing northward climb back to its high point at the summer solstice. That’s why the planet is much higher and easier to see.

Because Venus orbits between the sun and Earth, we get to see go through phases like the moon as the angle between it, us and the sun varies during Venus 225-day long orbit. Illustration: Bob King

As I described in a recent blog, telescope users can see Venus’ phase if they look at the planet during early dusk before it gets too low for a sharp view. Its currently a “half moon” as seen from our perspective here on Earth. Over the coming weeks, Venus will appear to get closer and closer to the sun at the same time as its phase changes from half to crescent.

I wish you well in your search for this somewhat elusive planetary goddess. If you succeed in finding her, please let us know.

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Pull up a chair for tonight’s Jupiter-moon palooza

Posted on August 26, 2010 by astrobob

Clouds fly by the moon earlier this week in this 25-second time exposure. Jupiter is the bright "star" just above the tree. Details: 20mm lens, f/5 at ISO 200. Photo: Bob King

At least in the Duluth, Minnesota region, it’s been clear night after night, allowing us to watch the daily rising of the moon and its changing phase. Tonight the moon lines up for a wonderful conjunction with the planet Jupiter. Both are brilliant and eye-catching guaranteeing a splendid time for all. The pair will be up around 9:45 p.m.  in the east, but if you wait until 10:30 or later, they’ll be easier to see after having cleared any treetops and buildings.

The waning gibbous moon and brilliant Jupiter will pair up tonight for a pretty sight. Maps created with Stellarium

If good fortune brings you clear skies, take out your binoculars and point them at any bright star, bring the star to a crisp focus and then aim them at Jupiter. If you’re using a magnification of 7x or higher (typical for binoculars) you should be able to see several of Jupiter’s brightest moons. You’ll need to hold them steady so the image doesn’t bounce around. I like to scrunch up against a wall for support but have been known to set the binoculars on the roof of my car, too. Whatever works for you. Once you’re focused in, look very close to the left or east of the planet and you should see several tiny “stars”. Tonight the moons Io and Ganymede will be very close together and so appear as a single “star” to your eye. You’ll need a small telescope to resolve them into two.

Try finding several of Jupiter's brightest moons in binoculars. Each number stands for a moon. IV is Callisto, II Europa, III Ganymede and I Io. Each is approximately the size of our own moon.

Each of Jupiter’s moons has its own period of revolution around the giant planet ranging from 1.8 days for innermost Io to 16.7 days for Callisto. That means they’re always on the move forming new arrangement every night you look. The map below depicts where they’ll be tonight, but if you’d like to know which is which on any given night, click on this Jupiter’s Moons utility to find out.

A friendly and relatively painless observing challenge would be to identify all four of the moons and even make sketches of their changing positions over a week’s time. Hey, wait a second – that’s exactly what Galileo did when he discovered them just over 400 years ago. He likened them to a solar system in miniature, a sight you can easily see for yourself by walking in the great Italian’s footsteps.

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The space station cruises over a roof near you

Posted on August 25, 2010 by astrobob

Engineer Shannon Walker works on the Smoke Aerosol Measurement Experiment inside the Microgravity Science Glovebox this week. The study may help engineers to design better smoke detectors for future spacecraft. Credit: NASA

The International Space Station (ISS) returns for evening viewing this week. When you go out to watch the craft silently glide across the sky, the astronauts aboard will be catching up on science experiments that were put on hold following the failure of an ammonia pump that shut down half the station’s cooling system at the end of July. A new pump was put in place last week and everything’s up and running.

Outside of Venus and the moon, the ISS is the brightest object in the sky and easy to see even from most cities – if you know when and where to look. The station orbits in the direction of Earth’s rotation or west to east. Passes can happen across the southern and northern sky, but it will always be moving toward the east and appear a brilliant star. If you notice a warm, yellowish hue to the craft, you’re seeing color from the multiple solar arrays which are golden-orange. They provide all the power needed to run the football stadium-sized station.

The ISS' solar arrays lend the spacecraft a distinctly warm color. Credit: NASA

As the ISS passes by, keep an eye out for flares. These occur when sunlight strikes a shiny part of the vehicle and reflects it straight back to your eyes. Veteran space station watchers will also see the occasional “water dump” when the astronauts dump unneeded waste water overboard. It quickly crystallizes into a cloud of ice particles which can give the appearance of the comet tail trailing the spacecraft.

The times below are Central Daylight and apply to the Duluth-northern Minn. – NW Wisc. region. For times for your town, please visit the Spaceweather satellite link and key in your zip code. You can also log on at Heavens-Above, select your city and get a more extensive list of predictions for both the ISS and other bright satellites.

* Tonight (Weds) at 8:31 p.m. Cruises low across the south and passes near
the rising moon about 8:34 p.m. A second brighter pass occurs at 10:04
p.m. when it makes a brief appearance in the western sky
* Thurs. Aug. 26 at 8:57 p.m. A fine, brilliant pass across the south
* Fri. Aug. 27 at 9:24 p.m. Best of the week! Nearly as bright as Venus; cruises straight across the top of the sky
* Sat. Aug. 28 at 8:16 p.m. Another brilliant pass in twilight. Glides
very close to Altair, the southern apex of the Summer Triangle about
8:19 p.m. Second pass in the northern sky at 9:52 p.m. when it cuts
across the handle of the Big Dipper
* Sun. Aug. 29 at 8:43 p.m. Another bright one across the top of the
sky. Second pass at 10:19 p.m. when it makes a brief appearance in the northwestern sky

Kody's eye lights up with magnified moonlight last night as he looks through the eyepiece of a 10-inch reflecting telescope. Photo: Bob King

It’s always fun when I can get a family member out to look through the telescope. Last night my daughter Maria and her boyfriend Kody spent a few minutes at scope-side looking at the full moon and Jupiter. Maria showed Kody a favorite trick for finding the moon or sun without using a finderscope or looking alongside the telescope tube. While staring at the ground behind the telescope, you move the tube up and down and back and forth. When the tube shadow is smallest, look in the eyepiece and voila, there’s the moon. Guaranteed to work every time.

After we finished our moon viewing, all three of us walked away with one temporarily blind eye apiece – a small price to pay for a trip to the nearest celestial body to Earth.

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Full moon fun plus astronomers discover new solar system

Posted on August 24, 2010 by astrobob

The nearly full moon shines from inside a corner of Duluth's iconic Aerial Lift Bridge last night about 20 minutes after sunset. 300mm lens at f/5.6, ISO 400, 1/60 second exposure. Photo: Bob King

Partly cloudy skies made for an interesting moonlit walk last night. I noticed that when the moon disappeared into clouds and then returned, the effect was more dramatic than when the sun does the same. Maybe it’s just me, but there’s a slight feeling of dread when the moon vanishes behind clouds. The light goes out, night suddenly grows deeper, and a bit of one’s inner cheer drains away. Briefly. The moon returned as it always does and lit the pines and spruce brightly enough to see their dark greens.

The Full Moon will light the night tonight. If you want to watch or take pictures, click on the link on the right side column of my home page for moonrise times for your city. In Duluth, the moon comes up at 7:43 p.m. and should make a striking sight above the blue waters of Lake Superior around 8 p.m.  Taking pictures of the moon during early twilight is easy because its brightness neatly matches that of the sky. Find an interesting foreground scene and then just point and shoot! If you use your camera’s wide angle lens setting, the moon will appear very small in the frame. Try to find a scene where you can zoom in – to make the moon bigger – while at the same time including something clearly recognizeable in the foreground.

About the time the moon starts to look bright and shiny to your eyes, the wide difference in exposure times between it and the darker foreground can cause problems. Exposing for the scene will give you a too-bright, overexposed moon while exposing for the moon will make for a dark foreground scene. Catch it at the right time and your picture will look very close to what your eye saw. Anytime during the half-hour after sunset should work.

The moon joins the brightest stars in the south and Jupiter in the east tonight. This map shows the sky around 10:30 local time. Created with Stellarium

As twilight deepens to night and the moon takes a commanding position in the southeastern sky, take another look. You’ll see that it’s part of a very large kite-shaped asterism that includes Jupiter, off to the left, and Altair, Vega and Deneb higher up.

The European Southern Observatory (ESO) announced today that astronomers using the 3.6-meter (142-inch) telescope at LaSilla, Chile, and an advanced spectrograph, detected a new system of extrasolar planets around sun-like star HD 10180, located 127 light years away in the southern constellation of Hydrus the Lesser Water Snake. At least five planets, each about the size of Neptune, have been found orbiting the star at very close distances ranging from 5.6 to 130 million miles. For comparison, the Earth is 93 million miles from the sun. The five planets, their orbits and sizes were deduced after six years of studying the tiny and complex gravitational tugs they exert on their host star.

Artist's impression of the planetary system around the Sun-like star HD 10180. Credit: ESO

The data also seem to point to the existence of two more planets for a total of seven in all, nearly as many as our own solar system. One of them may be the smallest exoplanet yet detected with a mass only 1.4 times greater than Earth and orbiting a mere 1.9 million miles from its sun.

The Holy Grail in extrasolar planet detection is finding Earth-sized bodies at the right distance from their central stars where, as the Goldilocks story says, the porridge is neither too hot nor too cold but just right . While this possible new planet is similar in size to our own, its proximity to its host star would probably cook life’s goose. No matter. We’ll keep hunting – that’s something we humans do well.

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