Comet Lovejoy pokes its head above Arizona’s horizon

Posted on January 26, 2012 by astrobob

Multiple time exposure pictures were "stacked" together to make this deep image of Comet Lovejoy. Some of the "black snow" is camera noise, much of it is very faint stars. The bright star Sirius is at upper right. Click image to see Rob's nice website devoted to the comet. Credit: Rob Kaufman

A question from a reader this morning stirred me to post this update on Comet Lovejoy, the great sungrazing comet of 2011. While the brightest part of the tail near the nearly-vanished head of the comet is now visible from the southern U.S., it’s exceedingly faint. I know of only one observer at this time who has succeeded in seeing it – Alan Hale, co-discoverer of one of the best known comets of our time, Comet Hale-Bopp. Twice this past week he used a 16-inch telescope to eke out the extremely faint glow of the comet’s head / tail. His first observation was made Sunday night:

“I had excellent sky conditions right down to the horizon. There definitely seemed to be an extremely pale and vague glow — not much more than a brightening of the background sky, but it seemed to be real.  It almost precisely followed the expected rate and direction of motion during the 1 1/2 hours that I followed it,” wrote Hale in an e-mail today.

He spotted the same faint glow last night (25th) moving in the same direction. Both times Hale estimated its brightness at 12.0, but because the comet’s light was so spread out, it was much more difficult to see than a typical smaller 12th magnitude comet.

Comet Lovejoy in its glory days photographed from Australia on Dec. 26, 2011. Credit: Rob Kaufman

From the southern hemisphere, where Comet Lovejoy is much higher in the sky, amateur astronomer and comet discoverer David Seargent spotted it with large 25 x 100  and 15 x 80 binoculars on Sunday the 22nd. His description matches Hale’s – a very faint glow. Meanwhile, astrophotographer Rob Kaufman of Australia pushed his camera equipment to the limit to record an impossibly faint 26-degree long tail. His picture (above) is a negative image to better show the contrast between comet and sky. What’s cool about the photo is that the tail pokes north almost to Sirius in the constellation Canis Major, stars widely visible from anywhere in the U.S. and southern Canada.

Pity that the better part of the tail is simply too dim to be seen with naked eye, binoculars or telescope. Unless you live in the far southern U.S. and have a moderate to large telescope, your chances of seeing Lovejoy are rapidly diminishing if only because the moon’s phase is waxing.

Comet Lovejoy on Dec. 22, 2011 reflected in water. Credit: Colin Legg

Bright moons kill faint comets. By the time Comet Lovejoy is high enough to be better placed for viewing in the mid-northern states next week, the moon will be on its way to full, making it impossible for anyone to spot it.

When the moon finally departs the early evening sky around Feb. 9, many amateur astronomers will be out for one last try at a visual observation. I’ll be among them. Even though Lovejoy will continue moving farther from Earth and fading in the coming weeks, I remain hopeful.

If you live in Arizona, Florida and other southern regions of the U.S. and Central America, now’s the time to seize the opportunity.

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Beautiful aurora! What makes it happen?

Posted on January 25, 2012 by astrobob

An amazing aurora display in northern Sweden last night. Details: Nikon D7000 camera, Tokina 11-16 2.8, ISO 1600, 5 second exposure. Click the photo to see his fantastic video of the entire night. Credit: Chad Blakely

Clouds! They were with us last night, but according to Mike Thiele, who observed from northwestern Minnesota, the storm had spent itself by the time it was night along the U.S.-Canada border: “Very weak display partially obscured by clouds about 4 a.m.,” he writes.

Earlier, during afternoon hours North American time, auroras raged across northern Europe. Sky watchers there called it one the best in years. Chad Blakely, who participated in the Lights over Lapland photo expedition in Abisko National Park in Sweden called it one of the most spectacular displays of aurora he had ever seen. “Words can not describe the excitement we shared and the sights we saw,” said Blakely.

Magnetic fields on the sun channel solar plasma - a hot gas composed of electrons and protons - into picturesque loops. Credit: NASA

Chad, I believe your photo negates the need to fumble with words. It’s a beautiful image that makes all wish we were there.

The storm and its wonderful auroras were on the fade by evening over the U.S. Though the intensity picked up a bit in the wee hours this morning, it never approached the levels seen in northern Europe and Siberia.

According to C. Alan Young, a NASA solar physicist, not all of the material speeding from the sun arrived at Earth. Rather we were struck by a more glancing blow. Had it been a direct hit in the right orientation for greatest storm effect, auroras would probably have been widespread across the U.S. as well.

As of 1 p.m. CST Earth’s magnetic bubble or magnetosphere is still reverberating from the shock with elevated levels of magnetic activity but nothing approaching a storm. The NOAA Space Weather forecast still calls for possible major storms with accompanying auroras today through tonight. If your weather is clear, I encourage you to look to the northern sky again tonight.

The normal solar wind of electrons and protons as well as faster-moving blasts caused by explosive solar flares sends material earthward, where it encounters our magnetosphere. Much of the plasma is deflected, but some creeps in through the tail-end or magnetotail. Credit: NASA

Billions of charged particles from the sun in the form of a coronal mass ejection (CME) are the first step in the making of a geomagnetic storm. Powerful explosions on the sun’s surface called solar flares launch this extremely tenuous cloud of material out toward the hapless planets at something like a million miles per hour. Yesterday’s CME was much faster – 4.5 million mph. The faster the particles travel, the sooner they arrive and the more energy they carry. Exactly like a speeding car. A crash at 10 mph is far less destructive than one at 65 mph. That’s why scientists predicted such a powerful storm yesterday.

When the cloud arrives in Earth’s vicinity it first bumps up against and then flows around the planet’s magnetosphere, a teardrop-shaped bubble of invisible magnetic energy much like the field around a typical refrigerator magnet. The magnetosphere is squished by the solar wind on the day side facing the sun and stretched out into a long ‘magnetotail’ on the night side of Earth.

Earth’s magnetic field is generated by the spinning of our iron-nickel core as the planet rotates on its axis. Hands down it’s the best defense we have against what the sun might throw at us. If Earth lacked a magnetosphere, high speed plasma clouds and the sun’s daily “solar wind” would sooner or later strip away our atmosphere with nasty consequences for all.

Illustration of electrons trapped inside the tail of Earth's magnetic field accelerating toward Earth's upper atmosphere to discharge in "sparks" of aurora. Credit: NASA

ANYWAY … the billions of charged particles – and we’re talking mostly electrons (negative charge) but also protons (positive charge) -  slide around the magnetic bubble, compressing and increasing its energy. Think of the air getting warmer as you pump a bicycle tire full – the air heats up from compression.

Meanwhile, some of the particles streaming past the bubble manage to link into the lines of magnetic force down at the tail end. The combination of compression and charged particle build-up on the opposite end of the magnetosphere generate powerful electric currents that push electrons toward the Earth’s magnetic poles at extremely high speeds. Something very similar happens in an old TV picture tube, where electrons are accelerated by thousands of volts toward a phosphor-coated screen. When they hit, the screen glows.

As they race earthward down magnetic field lines, the particles strike the upper atmosphere and crash into nitrogen and oxygen molecules some 50 miles or more overhead. The molecules are briefly excited to higher energy levels like someone buzzing with excitement during the reading of the daily lottery numbers. Moments later all those billions of oxygens and nitrogens return to their original “rest” states by losing energy in the form of green and red photons of light.  These are the colors of the aurora.

And what do we experience? Arcs, rays, spears of fast-moving color as solar plasma flies down those field lines and discharges all that pent-up electricity in bursts of molecular color. What a wonder that something so “mechanical” in nature could inspire so much awe. Such is the beauty of reality.

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Things to see while waiting for the storm to hit

Posted on January 24, 2012 by astrobob

A very thin moon only a day and a half past new appears in the southwestern sky shortly after sunset this evening. Created with Stellarium

* UPDATE 10:30 p.m. CST: The Kp index, which measures magnetic activity and the potential for auroras, reached storm levels of 5 this afternoon but has since dropped to an “active” but non-storm level of 3 for the past six hours. Earlier, auroras flickered over Scotland, northern Ireland, Scandinavia and the Arctic regions. For now, they appear to have moved further north into Canada. I’ve heard of no sightings YET from the northern U.S. Let us know what you see. Thanks!

While we’re waiting for the hoped-for light storm, let’s look ahead to things we can see and predict with certainty. Tonight for instance, you can stand outside and face southwest a half hour after sunset to see a temptingly delicate crescent moon in the west below Venus. It’ll be so thin that in bright twilight, it’s barely there. By tomorrow night the 25th, watch for the moon to thicken a bit and brighten further as it scooches up next to Venus.

Comet Garradd shows a pale green coma and two tails in this photo taken on January 16. Ion tail to the upper right (n.west) and dust tail (east). Credit: Erik Bryssinck

Remember Comet Garradd from last summer and fall? With the staying power of a marathon runner, it’s returned to the morning sky still clicking through the stars of Hercules the Strongman. No moon will spoil the darkness for the next 10 nights, so you may want to go out for a look.

Garradd will be easy to pinpoint thanks to some handy guide stars, and at magnitude 6.5-7 it’s bright enough to see in binoculars. A few mornings ago the comet was a small ball of glowing fuzz in 8×40 binoculars, while a look through my 15-inch scope made my eyeballs smile. At low power, the pale green coma with two soft, diffuse tails sticking out either end was a beautiful sight. I figured it was time to share.

Find Vega and then use the star Gamma in Draco and draw an imaginary equilateral triangle that includes Comet Garradd. The map shows the sky facing east around 5 a.m. local time.

The best time to observe Comet Garradd is when Hercules is highest in the east before the start of dawn or around 5-5:30 a.m. You can start by finding the bright star Vega of Summer Triangle fame in the east-northeast. From there, navigate up to the trapezoidal pattern of stars nicknamed the “Keystone” of Hercules. One side of the Keystone features the sumptuous globular cluster M13. The comet lies along the other side and moves slowly northward in the coming weeks. Let us know if you have success in seeing it.

Use this detailed chart to pick your way to the comet with binoculars and telescope. Star shown to 7th magnitude. Positions are at 5 a.m. Central time every five days. Created with Chris Mariott's SkyMap software

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Big solar storm, possible auroras on the way

Posted on January 23, 2012 by astrobob

The M9-class solar flare (upper right) photographed around 10 p.m. Sunday night by NASA's Solar Dynamics Observatory in ultraviolet light. Credit: NASA

A large, long-duration M9-class flare that began around 10 p.m. Central time Sunday January 22 blasted a supercharged cloud of plasma called a coronal mass ejection in Earth’s and Mars’ direction. Traveling at 4.5 million miles per hour, it’s expected to arrive tomorrow morning (Jan. 24) though it could arrive 7 hours earlier or later. Earlier would mean late tonight for the U.S. and Canada. The flare, one of the most powerful in the current solar cycle, originated in the same sunspot group as the earlier flare that spawned last night’s auroras.

The NOAA Space Weather forecast calls for periods of severe and major geomagnetic storming on both January 24 and 25 with calm conditions returning late on the 26th. What does this all mean? Well, for one, sky watchers in the northern U.S. are almost certain to see a great show of northern lights. A big storm also could blackout radio communications between airplanes crossing polar regions (flights are rerouted), damage sensitive satellite electronics, affect the accuracy of GPS devices and overload power grids, particularly those in Canada, Alaska and the northern states.

The auroral oval photographed via satellite in ultraviolet light. The oval is a permanent feature in Earth's ionosphere but shrinks or expands in response to plasma clouds arriving from the sun. Credit: NASA

I’ll be monitoring the progress of the storm as I hope – like you -  that skies will be clear. Here are a few other useful websites you might want to check out to stock your info larder:

* Real-Time auroral oval. This site shows you the position and extent of the “crown” of strong auroral activity in the Earth’s north polar region called the auroral oval. If you’re under the oval, you see the aurora every dark night of the year. Normally this glowing green donut stays way up in the Arctic, but if you see the oval expand southward into the U.S., it’s time to drop what you’re doing and head outside to look for northern lights.

The storm of streaks is from an image taken by SOHO's coronagraph are caused by high-speed protons from the current storm hitting the the camera's sensor. Credit: NASA/ESA

* 3-day Kp index. Indicator of magnetic activity in the Earth’s magnetosphere or magnetic bubble. If the index bar is yellow with a value of 4, activity is increasing. If the bar is red with a reading of 5 or higher, chances of seeing an auroral display is very good — at least from the northern U.S.
* POES auroral oval plot. Data from the POES satellite is used to create an image of the auroral oval. If the oval is large, red and near the region where you live, you have a good chance of seeing northern lights.
* Aurora FAQ. Lots of answers to your questions.

After checking the data this evening, I can already see that activity levels are going up and the storm is starting. How exciting. It’s almost like a summer thunderstorm when you were a kid – a little scary but you knew you were safe. That’s true with this geomagnetic storm too. We’ve been through ones like it before. While there may be some disturbances as described above, the most pain you and I will show for it are a few lost hours of sleep and stiff necks from craning our heads skyward.

Stop back for more information as the story develops.

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Mars shifts gears as it approaches Earth

Posted on January 23, 2012 by astrobob

Aurora borealis over northern Norway last night. Credit: Øystein Lunde Ingvaldsen

Last night’s aurora graced the skies of Canada, Alaska, Scandinavia and even Ireland. Perhaps you saw it, too. We were cloudy in my town but that won’t stop me from sharing a striking image shot by Øystein Lunde Ingvaldsen of northern Norway. A combination of good weather and lots of activity made for a powerful display. The effects of the solar flare will taper off tonight, but it now appears we’re in for round two.  A burst of particles from another large flare late on Jan. 22 will reach Earth sometime tomorrow and produce auroras that likely will reach down into the U.S. I’ll have more on this in tomorrow’s blog.

If you could float in space above the plane of the solar system, this is how Mars and Earth would look during late January. Shortly before the two planets make their closest approach to each other at opposition on March 3, the Red Planet appears to stop and move backwards in the sky. Illustration: Bob King

We normally see Mars (and all the outer planets) move eastward through the sky as they orbit the sun, but something odd happens around the time of opposition. That’s when Earth and the Red Planet are lined up on the same side of the sun and closest to one another.  This tete-a-tete occurs every two years and will again this year on March 3. As the two planets combined orbital motions bring them closer together, Mars has been steadily brightening and appearing larger over the past few months. It currently outshines every star of the night except Sirius and Canopus.

The planet Mars retrogrades or "backs up" through the constellation Leo beginning tomorrow. Created with Chris Marriott's SkyMap

As we approach the March opposition,Earth, which is closer to the sun and moves faster than Mars, slowly overtakes the slower planet. From our perspective, we see Mars appear to slow down, stop and “put it in reverse”, moving to the west for a time. When an outer planet appears to stop moving in the sky, we say it’s “stationary”. For Mars that happens tomorrow January 24. Slowly at first, but then with increasing speed, Mars backs up to the west as Earth passes. Think of passing a slower car on the freeway. As you move into the left lane and accelerate, the car appears to be moving backwards as you zoom by. Astronomers call this backwards movement retrograde motion.

Mars will retrograde through early April as it inches its way northward toward Leo’s brightest star Regulus. Once Earth and Mars have sufficiently separated, Mars will resume its usual eastward motion among the stars. To see a wonderful animation of how it all happens, please click HERE and press the RUN button.

This animation shows how ancient astronomers explained retrograde motion. Each planet moved in a smaller circle superimposed on its larger orbital circle. (Animation from Dr. Stephen J. Daunt's Astronomy 161 website at Univ. of Tennesee, Knoxville.)

Retrograde motion confounded ancient astronomers given the accepted model of the solar system at the time with Earth at the center and all the planets, including the sun, revolving around it. To explain how a planet could back up and make an about face, they had to postulate separate, smaller circular orbits called epicycles (left) superimposed on the planet’s main orbit. This gears within gears approach eventually became so complicated, logical-minded folks figured there had to be another way. Enter Nicholas Copernicus, who helped clean up the mess when he published his sun-centered solar system theory in 1543, but that’s another story.

Astrophotographer Tunc Tezel combined many images of Mars taken before, during and after opposition in 2003 to show its wonderful loop-de-loop movement in the sky. A similar but flatter loop is made by the much more distant planet Uranus, seen at right. Credit: Tunc Tezel

There’s a nice little benefit that comes with retrograding. Mars’ eastward motion means it outpaces the natural earlier rising time of stars with each passing night. Regulus and Leo rise much earlier now than they did a couple months ago. Mars meanwhile has been “running away” to the east during much of this time, delaying its rising time and requiring sky watchers to stay up late to see it. No more. The planet will soon be moving west and rising slightly sooner than the stars, making it easier to see during earlier evening hours.

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Aurora alert tonight

Posted on January 22, 2012 by astrobob

A flare from sunspot group 1401 kicked out a CME - coronal mass ejection - in the Earth's direction on Jan. 19. Its arrival today has sparked auroras. Credit: NASA/ESA

It’s overcast here in Duluth, Minn. and looks to remain so overnight, but if you live in the northern U.S. or Canada, seeing an aurora tonight is a distinct possibility. As of 4 p.m. Central Time, the Kp index, a measure of how active or disturbed the Earth’s magnetic field is, has climbed into the “red zone” with Kp=5. That means a geomagnetic storm with accompanying auroras is in progress. Looking at the real-time aurora map, you can see that Siberia, Scandinavia, Scotland, and Greenland and parts of northern Canada are already under a cap of northern lights.

POES satellite map of aurora at 3:29 p.m. CST today. Credit: NOAA

The map at right was made with data from the Polar Operational Environmental Satellite (POES) and shows high magnetic activity (aurora) across much of the far north. The red arrow indicates where it’s local noon.

If there’s any chance for a clear sky at your house, pop out for a look tonight. There’s no moon in the sky, so it’s an ideal time to watch an auroral display — assuming it keeps on coming.
** Update 1: Aurora is still active this evening as of 8:30 p.m. CST but appears to be north of 50 N. latitude into Canada. It’s early yet.
** Update 2: If it were clear in northern Minn., my hunch is that aurora would be visible in the northern sky at this hour (11 p.m. CST). Activity is still up and aurora appears to be out across a good part of Canada.

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Winter binocular tour of the Milky Way mansion

Posted on January 22, 2012 by astrobob

In and around the bright Winter Hexagon (outlined) are 11 deep sky objects bright enough to see in just a pair of binoculars. The blue circle guide is about 5 degrees across, the field of view of a typical pair of binoculars. The map covers the entire southern sky from horizon to overhead. Created with Stellarium

Not long ago we visited the Winter Hexagon and all the bright stars concentrated in the southern sky this season. This great abundance of jewels is the real reason why the stars seem to be so much brighter compared to the other seasons. That’s not all. Tucked in and around the Hexagon is one of the greatest concentrations of bright deep sky objects visible anywhere in the sky.

Deep sky objects are everything that’s up there besides the stars and solar system offerings – all the galaxies, star clusters and nebulae in the universe. Hunting up the brighter ones in your binoculars will give you a deeper appreciation for the richness and diversity of our Milky Way and a taste of what lies beyond. It’s like going to the next level in a video game only you’re looking at real things. Much better.

My pair of 8x40 binoculars. Photo: Bob King

And yes, I do mean binoculars. From a moderately dark sky, you should be able to see all 11 of the “M” objects I’ve plotted on the map above.  Just to be sure, I did a reality check Friday night with an inexpensive pair of Nikon Action Touch 8×40 binoculars, which are very middle-of-the-road as far as light gathering power and magnification. With no moon to brighten the sky and moderate light pollution in the south, I didn’t have to strain to see any of them. Several, like M42, M45, M41 and M37 were even visible with the naked eye.

“M” stands for Messier as in Charles Messier, an 18th century French astronomer who compiled a catalog of 110 fuzzy and starry patches he stumbled across while hunting for comets. Because he only used a small 4-inch telescope, Messier discovered most of the sky’s brightest and prettiest deep sky objects. His comets have been mostly forgotten, but the Messier catalog has become the night sky’s hit parade.

Like many beginning astronomers, I became acquainted with the Messier objects after first looking at the moon and bright planets. A few were too faint to see from my suburban Chicago home, so I’d bring the telescope along when our family would vacation in northern Wisconsin and make good use of the dark sky. By the late 1960s, I’d seen them all.

Photos of four of our Messier objects taken through the telescope. Open clusters are loose groups of bright, young stars formed from gas and dust in the Milky Way's spiral arms. The blue disk in M46 is the planetary nebula NGC 2438, visible in a telescope.

In astronomy, once you’ve seen something once doesn’t mean you’re done. You return to see that cluster or galaxy again and again just as you would a favorite photograph, painting or book. Should you buy a larger telescope, you’ll eagerly point it at each Messier once more to see what new details might be revealed. I’ve been in the hobby for nearly fifty years and still look at the Orion Nebula (M42) nearly every clear winter night.

The Orion Nebula or M42 is just below Orion's Belt (top) in the middle of his "sword". In this time exposure it looks pink but through binoculars the nebula appears as a misty patch dotted with several stars. Photo: Bob King

Of the 11 deep sky objects plotted, all are found within the Milky Way galaxy. 10 are open clusters — assemblages of young stars born from clouds of gas and dust called nebulae and held together in bunches by their mutual gravitational attraction. The remaining object is the Orion Nebula, is a cavernous gas-dust cloud 1350 light years from Earth and 24 light years across located directly below his famous “three-stars-in-a-row” belt.

Within its folds and swirls, new stars and planetary systems are congealing as I write this. In the remote future, the dust will be gone, leaving a rich cluster of stars much like the other Messier objects on our list.

By far the easiest Messier object is M45, better known as the Seven Sisters Star Cluster or the Pleiades. That you can find with your naked eye, but don’t pass up the chance to see it in binoculars. You’ll be amazed at how many more stars are hiding there just below the naked eye limit.

This photo, taken Friday night, shows the constellation Canis Major the Greater Dog with three Messier clusters. The dog's head is the triangle at upper left; his feet stick out to the right side of and below Sirius. Photo: Bob King

The map shows the star clusters as fuzzy spots, and that’s just what they look like at first glance. If you take care to focus your binoculars sharply, you’ll have no problem seeing individual stars in several of them. The easiest to resolve into tiny pinpoints are M41, M44 (also called the Beehive Cluster), M47 and M35. M46 and M50 are fainter and may take a little (but just a little) more effort to see. M41 is a particular favorite of mine, because it looks so sparkly and rich compared to its more “spread out” appearance in the telescope.

In this illustration of the Milky Way galaxy based on recent findings, many of the bright clumps represent open star clusters in its spiral arms. This image is copyright Mark A. Garlick and has been used with permission. Please do not use this image in any way whatsoever without first contacting the artist - thanks! www.space-art.co.uk / www.markgarlick.com

From a dark sky, you’ll even see the faint band of the winter Milky Way streaming down from near Capella at the top of the sky through Gemini and eastern Orion and past Sirius. Many of the clusters are situated within our galaxy’s spiral arms. If we could zoom away from our galaxy and look back, they would stand out as bright clumps like lights  strung around a Christmas tree. We live in a grand place – put on your coat and come tour the mansion overhead.

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Astronauts in perpetual twilight as space station returns to view

Posted on January 21, 2012 by astrobob

This picture of the Earth's terminator, the fuzzy boundary between day and night, was taken from the window of the space station recently. The astronauts on board will spend a lot time in the coming week flying over this zone of perpetual twilight. Credit: NASA

Astronaut Don Pettit’s latest blog entry from his current stay aboard the International Space Station (ISS) is an interesting one. Pettit, a flight engineer, describes this time of year as one of perpetual twilight for him and his fellow astronauts. Twice a year around the time of the solstices, the orbit of the ISS nearly parallels the Earth’s terminator. In his own words:

“For a period of about a week, we live in what seems like perpetual twilight, being in neither full daylight nor full night. Our orbit follows the terminator, so that the space station is constantly sunlit. From this vantage I can see both day and night simply by swiveling my head from left to right. But the night is not really dark, and the day is lit by low-angle rays from the sun.”

It almost sounds like a description of our winter except for the 24 hours of sunlight part. Pettit describes other peculiarities:

How many layers of blue can you see in this photo taken from the ISS recently? Credit: NASA

“The Moon sets in a counterintuitive way. From this vantage it moves nearly parallel to the horizon. Once I saw it slowly set, only to reappear in a few minutes. The Moon was visible for nearly the whole orbit. The night side is equally fascinating. The atmosphere on edge glows with a vibrant electric blue. Did van Gogh paint this scene? I can see at least five, maybe six distinct layers of blue—perhaps a visual display of the classic atmospheric strata.”

We can imagine Don musing out the window during his down time, because the space station is making a new series of bright passes in the morning sky  The times listed below are for the Duluth, Minn. region. For your town, please click HERE and enter your zip code or log on to Heavens Above, which includes sky maps for every pass. The ISS moves from west to east and typically appears as bright as Jupiter. Its large orange-colored solar panels give the craft a yellow hue.

* Sunday morning Jan. 22 beginning at 6:16 a.m. across the northern sky. Very bright!
* Monday Jan. 23 at 6:54 a.m. similar to above
* Tuesday Jan. 24 at 6 a.m. Appears out of Earth’s shadow below and west of the North Star
* Wednesday Jan. 25 at 6:38 a.m. Another pass across the north
* Thursday Jan. 26 at 7:16 a.m. in twilight. A high,brilliant pass — peak magnitude -3.0!
* Friday Jan. 27 at 6:21 a.m. in the northern sky
* Saturday Jan. 28 at 6:59 a.m. straight across the top of the sky. Another brilliant appearance!

A very "old" crescent moon punctuates the twilight sky earlier this morning seen from Duluth. Photo: Bob King

I wish I could say you’ll have the company of the crescent moon when you’re out ISS-gazing, but by tomorrow it’ll be too low in the east before sunrise to see from Duluth. Floridians and others in the Sun Belt might still catch a glimpse of it. The following day the moon will be new and then coast back into the evening sky.

This morning was calm, cold and very clear. Saturn’s rings and moons and Mars’ north polar cap were stunning in the telescope. As the temperature sank to -14, I watched the star Altair finally clear the treeline in the east to complete the Summer Triangle. Yes, it’s back! Anytime you want to see what the starry future holds, just look up at dawn. It’s a whole different world up there.

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Warming up for Valentine’s Day, Eros flies by Earth

Posted on January 20, 2012 by astrobob

A video compiled of still images taken by the NEAR spacecraft in 2000-2001. The asteroid rotates end over end once every 5 hours and 16 minutes. Credit: NASA

With Valentine’s Day approaching, get into the spirit early by consulting with Eros, Greek god of love, now touring the constellation Sextans in the evening sky.

Asteroid 433 Eros was the first near-Earth asteroid (NEO) ever discovered back in 1898. Some NEOs zip just thousands of miles from our planet, but Eros will only come as close as 16.6 million miles or about 70 times the distance of the moon on January 31. That still makes this approach the closest since 1975 and the best until January 2056.

While it can shine as brightly as magnitude 7.0, this time around Eros will range between magnitude 8.6-9.0. That’s a little fainter than Neptune, so you’ll need good binoculars or a small telescope to see it. My 8×40 binoculars can reach down to 9th magnitude under dark skies. The key to seeing faint objects is keeping the instrument steady. You can mount your binoculars on a tripod, hold them atop a fence post or car roof or simply brace yourself against a wall.

A reconstruction of Eros using images from NEAR-Shoemaker. Stony meteorites called L4 chondrites might be derived from the rocks on the asteroid. Click image to see many more photos and animations. Credit: NASA

Eros is a rocky asteroid measuring 21 x 7 x 7 miles and shaped a bit like a slipper. The Near-Earth Asteroid Rendezvous-Shoemaker (NEAR) probe visited the asteroid and settled into orbit around it on – get this – Valentine’s Day 2000. The following January it passed within 1.5 miles of Eros’ surface snapping many closeup pictures of the cratered landscape. Then in mid-February NASA mission controllers gently brought it to the surface where it rests to this day. The last signals from NEAR were received on February 28, 2001 before it was shut down.

There is no air on Eros and temperatures range from a daytime high of 212 degrees (water’s boiling point) to a nighttime low of 238 below. Because of its small size and mass, a 200 lb person would weigh just two ounces there. Pick up and throw one of its many rocks at just 22 mph and it would escape into space never to return.

Wide field map showing Leo, Mars and your key star Rho Leonis around 10:30 p.m. local time facing east. Maps created with Stellarium

To spot the cruising space island, you’ll need to be out around 10:30 p.m. local time when the constellation Leo along with the planet Mars are up in the eastern sky. Locate the bright star Regulus at the bottom of the sickle-shaped head of Leo. About four degrees to the lower left of Regulus you’ll see a fainter 4th magnitude star named Rho Leonis. Once you find Rho, you can use the detailed map below to star hop to Eros.

The faintest stars shown on the map are about 9th magnitude or a little fainter than the asteroid, which shines at about magnitude 8.7 from now through mid-February.

Eros is moving fast enough that you can easily its motion to the south night after night. With a telescope magnifying around 100x, its movement is detectable in just an hour or so. In both instruments, Eros will look exactly like a star, since it’s too small and too far away to show a shape. I wish you luck in love in the coming weeks!

This detailed map shows Eros in relation to Rho Leonis as it tracks south in the next couple weeks. The positions shown are around 10:30 p.m. CST and won't vary much over a few time zones on a particular night. North is to the upper left, the way you'd see it facing Leo around 10-11 p.m. your local time.

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Subzero sun and a glimpse into the future

Posted on January 19, 2012 by astrobob

The sun rises through a bank of lake fog on Lake Superior near the Lester River on a bitter cold Thursday morning here in Duluth, Minn. Photo: Bob King

It wasn’t easy to feel the sun this morning with 19 below zero and a sharp northwest wind. No matter what the season, the sun’s brilliance remains the same, but you’ll strain to sense the warmer side of its personality on days like today. When the thermometer scrapes bottom in my town, Lake Superior exhales foggy breath just like people do. We call it lake steam or ice fog. Colder air blowing over the warmer open water suddenly drops in temperature; the water it’s carrying condenses into millions of wispy vapors. The swirls combine into clouds that rise into a tidal wave of steam in the distance. Raw, menacing, ethereal – pick your adjective. We love the apparition and consider it one of the many intangible reasons we choose to live here.

Photo of the sun taken at noon CST today by the Solar Dynamics Observatory. Several sunspot groups are visible including the lively 1401. Credit: NASA

After a period of doldrums, solar activity is picking up again with several picturesque and magnetically active sunspot groups dotting the sun’s face. In particular, Region 1401 has a busy, complicated mix of magnetic polarities (north and south magnetic poles) that’s been responsible for an ongoing series of flares. Once the group rotates more directly into our line of sight, we might see some effects on Earth. Meanwhile material from a January 16 coronal mass ejection (CME) is expected to touch our planet starting late tonight through the 20th. That means an increased chance for northern lights for observers at higher latitudes. If you live in the northern U.S. or southern Canada, it’s worth checking the northern sky both nights.

The Ring Nebula in the constellation Lyra is a classic example a planetary nebula. The remaining white dwarf is at center is the size of Earth but contains 1.2 x the mass of the sun. Credit: NASA/ESA

The sun is a middle-aged star with about five billion years of an active, exciting life remaining before it runs out of nuclear fuel. In the year 5,000,000,001 A.D. – give or take – the sun will sheds its outer layers to reveal a carefully kept secret – a tiny, compressed core called a white dwarf star. Though only as big as the Earth, a white dwarf is twice as hot and so fantastically dense that a teaspoon of the stuff would weigh as much as an elephant. Surrounding the dwarf will be a butterfly or ring-shaped cloud of gas astronomers call a planetary nebula. The name comes from its resemblance to the round shape of a planet.

The scenic cloud are the remains of the sun’s outer layers that will be expelled by powerful stellar winds during its tumultuous transition to white dwarfdom. Every time we observe a planetary nebula through our telescopes, we see the sun’s distant future.

ESO's Visible and Infrared Survey Telescope for Astronomy (VISTA) captured this unusual view of the Helix Nebula, a planetary nebula located 700 light-years away. The left picture was made through infrared filters. The telescope's infrared vision reveals strands of cold nebular gas that are mostly obscured in visible images of the Helix. Click to enlarge. Credit: ESO/VISTA/J. Emerson

European astronomers released a brand new photo today of the Helix planetary nebula in the constellation Aquarius taken in infrared light. The main ring of the Helix is two light years across and glows due to excitation from strong ultraviolet light emitted by the white dwarf at center. Each of the fine strands radiating from the nebula’s center span the size of our solar system and is composed of hydrogen molecules. To learn more about the Helix, please click HERE.

Assuming the Earth survives until the time the sun becomes a white dwarf, we’ll still revolve around it as always, but what we call “sun” will be only a pinpoint of white fire in a twilight-dark sky.

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