Monthly Archives: January 2012

Astronomy’s an adventure and don’t let anyone tell you differently

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Photo taken January 16 from the International Space Station of the 62-mile diameter Manicouagan Crater in northern Canada, one of the oldest impact craters known. The feature was formed about 200 million years ago. An ring-shaped lake fills the crater's outer rim. Credit: NASA

Dawn space station passes for the U.S. will wind down this week, so if you’re a morning person, the next few days will present several nice opportunities to see the magnificent flying machine. Starting this Saturday the station will be making daytime passes only until it returns to the evening sky on or around Feb. 12.

* Tomorrow February 1 beginning at 6:27 a.m. Fine bright pass across the southern sky. At 6:28 the ISS zips under the planet Mars and a minute later under Saturn. Enjoy the ride!
* Wednesday Feb. 2 at 5:33 a.m. Brief, bright pass in the south-southeast
* Thursday Feb. 3 at 6:11 a.m. Low pass in the south

These are viewing times for the Duluth, Minn. region. For times for your town, please login to Heavens Above or enter your zip code at Spaceweather’s satellite flyby site.

A computer-created illustration of Rochechouart crater shortly after its formation some 200 million years ago. Credit: Frederic Michaud

The crater shown in the photo was created by as asteroid about 3 miles in diameter between 206 and 214 million years ago. Geophysicist David Rowley of the University of Chicago along with several colleagues has proposed that the Manicouagan Crater may have been just one of five multiple impact craters that formed at the same time from the breakup of a comet or asteroid. The others are the Red Wing Crater in North Dakota (5.6 miles diameter), Saint Martin in Manitoba (25 miles), Rochechouart in France (13 miles) and Obolon’ in Ukraine (12 miles). To learn more about the many craters identified to date on planet Earth, click over to the Earth Impact Database.

The inset photo shows Comet Shoemaker-Levy 9 in January 1994 when it was shattered to pieces by Jupiter's gravity. Six months later the fragments fell into the planet creating a series of black, sooty scars in its upper cloud deck. Credit: NASA/Hubble Space Telescope

The idea is plausible based upon similar ages and alignment, taking into account tectonic plate movements in the intervening 200 million years. We’ve also seen something like this happen before but not on Earth. Between July 16 and July 22, 1994 Comet Shoemaker-Levy 9, which was captured by the planet Jupiter, broke up into multiple pieces which rained down in succession into the planet’s cloud tops. Flashes from the explosive collisions with the atmosphere were recorded by the Galileo spacecraft at the time. Back on Earth, amateur astronomers thrilled to the parade of dark impact blotches that ringed Jupiter like an onyx necklace.

The lines on the map show the path of the July 10, 1972 total solar eclipse. Credit: NASA

I have a personal story to share about the Manicouagan Crater area. On July 10, 1972 the centerline of a total eclipse of the sun passed just south of the crater. My buddies Rick and Larry and I were working in northern Wisconsin at the time and decided to drive up and see the eclipse. We bought a few groceries and piled into Larry’s green Vega for a very long drive across Michigan and up through Canada into Quebec. As I recall, we made a left turn inland at Baie Comeau on the St. Lawrence River and drove until we hit the inevitable dirt road somewhere in the middle of the forest near the centerline. There we set up camp along a river the evening before the eclipse.

I don’t remember when we noticed the black flies, but they became an increasing problem the next day. We wandered along the river looking for a scenic spot to watch the rare event that afternoon. Just before totality, clouds obscured the sun, leaving us with little more than a few minutes of pseudo-darkness. No spectacular corona, no flaming pink prominences, no once-in-a-lifetime spinal chill.

While this was obviously a disappointment, more disturbing were the flies. We were fresh Wisconsin sausage in their tiny eyes and they pursued us now relentlessly. I had so many bites on the back of my neck and ears my fingers were bloody from scratching.

We hurried back to take down the tent, literally ran for the car and got the hell outta there. My fondest memory of the event was relaxing in a bathtub later that night in a motel in Baie Comeau nursing my bitten body. Astronomy’s full of adventure and don’t let anyone tell you differently.

Ina Caldera – one of the moon’s coolest, hottest mysteries

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Ina Caldera sits atop a low, broad volcanic dome or shield volcano, where lavas once oozed from the moon’s crust. The darker patches in the photo are blobs of older lunar crust. They’re “domed” and rise higher than the rougher surface between them. Credit: NASA

In the March 2012 issue of Sky and Telescope magazine there’s a fascinating short article about a possible lunar volcanic landform called Ina Caldera. This 2-mile long D-shaped patch looks like nothing I’ve ever seen on the moon.

Blobs of older, crater-pitted lunar crust (darker blobs) rise some 250 feet above the younger, rubbly surface like melted cheese on pizza. Brighter areas on the moon generally indicate younger surface features. Solar and cosmic radiation darkens airless worlds like the moon and asteroids over the long haul of time. Not only is the bumpy region lighter-toned, but it appears to have far fewer craters, another sign of its relative youth.

Ina was first noticed only as recently as 1971 when photographed by the astronauts aboard Apollo 15. Recent photos taken by the low-flying Lunar Reconnaissance Orbiter (LRO) show a level of detail that reveal how unique this curious feature really is. So what’s going on in Ina?

Steam issues from the active volcano Nyiragongo in the Democratic Republic of the Congo in May 2010 as photographed by satellite. Credit: NASA

Theories abound. In a real volcano, calderas are caused by the collapse of material at the volcano’s top after magma from below has drained away following an eruption. Perhaps the top of the low volcanic dome on which Ina sits collapsed unevenly and relatively recently to form the patchwork we see today. Another possibility is that magma from below heated trapped gases like carbon dioxide and water to such high pressures, they violently blasted right through the crust, sending rock and debris flying for miles.

This photo shows the moon at 8 days old, but the lighting should be good on tonight’s 7-day-old moon to look for Ina. Ina is located just south of the arc of the Apennine Mountains in the moon’s northern hemisphere almost midway between the craters Conon and Manilius. Photo: Bob King

Other researchers with the LRO mission agree that Ina’s two terrains are a contrast of young and old but don’t think the brighter areas are as young as assumed. Additional high resolution photos from the orbiter show a good number of craters there (see photo below).  I encourage you to explore Ina yourself by going to the LRO’s ACT-REACT Quick Map and entering its latitude of 18.65 and longitude of 5.31. As you zoom in, you’ll feel as if you’re coming in for a landing.

Extreme closeup of a small portion of Ina’s interior. The smoother areas are rounded, blobby “islands” sitting atop the rougher terrain. Credit: NASA

Whatever happened created an enigmatic moonscape that scientists are still trying to understand. In so many ways, the moon is an undiscovered world. With just six short visits during the Apollo era and 150 lunar meteorites collected on Earth, we’ve barely scraped the lunar regolith.

You can appreciate how small the Ina Caldera is this spectacular closeup photo taken by Alan Friedman. Find the Apennines and Conon crater on the range’s southern flank, then navigate toward Manilius using high magnification. Click to see the complete high resolution image. Copyright Alan Friedman/avertedimagination.com

One of the constant joys of amateur astronomy is seeing with your own eyes what you read or heard about. And trust me, you can see much more than you might think. Even Ina. While most of you will explore via the ACT-REACT map, if you’ve got an 8-inch or larger telescope and you’re generally familiar with the moon, you can start hunting for Ina this evening. This tiny feature is most easily visible when light strikes it from a low angle as it will on tonight’s first quarter moon. If it’s cloudy tonight, try again over the next few nights. Hope for calm air, use high power and you might just be able to spot this enigma.

Moon, Jupiter, Mars strut their stuff tonight

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The half moon glides by brilliant Jupiter the next two nights. Map created with Stellarium

Cast a glance upward at the moon tonight. That big, bright object just a few degrees to its south is the planet Jupiter. The two will be sky buddies the next couple evenings.

Through binoculars the 6-day-old moon will reveal a variety of crisp-edged craters along the terminator, the boundary between lunar day and night.  Most prominent tonight is a remarkable chain of impact craters – Theophilus, Cyrillus and Catharina.

Theophilus is named after an ancient Greek geographer and measures 68 miles across. It fairly fresh as lunar craters go, with a sharp-edged rim and a couple of distinctive central mountain peaks. Theophilus overlaps the much older Cyrillus, which is 61 miles across and named for a 4th century theologian.

One of the best known features on the moon is the Theophilus crater chain. Watch for it tonight in a small telescope. Photo: Bob King

Scientists determine relative crater age by looking at which craters overlap others (the ones on top are younger) and noting how worn or broken their rims are. Cyrillus’s rim is worn down and much less crisp than Theophilus to the north. The final crater is the chain, Catherina, named for St. Catherine, a Greek theologian and philosopher, is 62 miles across and even more beaten down than Cyrillus.

Jupiter, its moon Io and Io's shadow tonight at 6:30 p.m. CST. South is up as viewed in most telescope. Credit: Meridian

You should be able to spot the trio in binoculars, but the best view will be through a telescope. And it doesn’t have to be a big one. Even a cheap department store scope will do the job. While you’re at it, point it at Jupiter. The two most prominent stripes – the North and South Equatorial Belts – are easy to see across the planet’s midsection. This evening the shadow of Jupiter’s moon Io will hover over the South Equatorial Belt from 5 to 7 p.m. CST. Look for a tiny, inky-black dot. Io itself will shine brightly nearby due west of the planet.

Finally, Mars rises around 8:45 p.m. and is high enough by 11 p.m. to have cleared the atmospheric muck for a sharp view. With a 4-inch or larger telescope magnifying around 150x, not only is the north polar cap a snowy white oval, but the planet’s most obvious dark marking, Syrtis Major, is front and center. This vaguely triangular patch is an enormous extinct shield volcano. Another easy feature to look for is the fat, dark rim along the polar cap called Utopia. The second of the two Viking landers touched down there in September 1976.

Even small telescopes can pick out some of Mars' more obvious features this week. Credit: Damian Peach

Because a day on Mars is 37 minutes longer than Earth’s, all Martian surface features gradually drift to the east as the nights go by. Tonight Syrtis Major and Utopia face us square on around 11:30 CST, tomorrow they’ll do so around midnight and on the 31st around 12:30 a.m. They’re also easily seen up to a couple hours before and after those times.

In the coming weeks, I’ll have more tips on how to observe the Red Planet as we approach opposition in March.

If it’s clear the next few nights, don’t miss this opportunity to spot several of Mars best landmarks.

The biggest star in the sky and how to see it

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Canis Major hosts the brightest star in the sky, Sirius, as well as our featured star VY. You'll find Sirius twinkling brightly about halfway up in the southern sky around 10 o'clock.

Astronomy is full of superlatives. Farthest, closest, hottest, densest, biggest, smallest. It’s fun to prowl around the sky in search of these extremes.

Two nights ago, I found myself star-hopping across Canis Major the Greater Dog in search of this or that gas cloud and spotted the star VY Canis Majoris on my atlas. The use of the lettered name “VY” tells us first off that this is a variable star whose light is not constant like the sun’s.

A quick check on the American Association of Variable Star Observers (AAVSO) website shows that VY varies between magnitudes 7.4 at brightest to 9.6. For the past few months it’s been around 8.0, bright enough to see in ordinary binoculars.

But its variability is not exactly the reason I wanted to acquaint you with this star. VY  is special for an entirely different reason – it’s the largest star known! Astronomers estimate its diameter at some 2,000 times the size of the sun. And since the sun is no slouch at 864,000 miles across, VY is truly a monster.

Illustration showing the size of the sun compared to VY Canis Majoris

Put in place of the sun at the center of the solar system, it would puff out beyond the orbit of Saturn. If the sun were reduced to the size of one of those big rubber balls people use as chairs these days, VY would be a much bigger ball 1.4 miles across. Yet another way to think of its vast girth is to compare how long it would take jet airliner traveling at 550 mph to fly across Earth, sun and VY:

* 14.5 hours non-stop to fly across Earth’s diameter of 8,000 miles
* 65.5 days to cross the sun
* 394 years to complete the 1.9 billion mile flight across VY

Thinking about that makes me want to stand up right now and stretch my legs.

VY is about 5,000 light years from Earth and classified as a red hypergiant star with a temperature of some 5000 degrees F. Surrounding the star is a small nebula of dust and gases VY has expelled in fits and starts during its evolution from a white supergiant star to its present state. Really big stars like VY eventually run of off nuclear fuel in their cores, collapse under the pull of gravity and then explode as supernovas. VY is so enormous that scientists predict it will one day become a powerful hypernova – ah, yet another superlative! – and might even collapse to form a black hole.

Use this detailed map, which shows stars to about 8th magnitude, to star-hop to VY and two other sky delights. North is up. Click map to go to the AAVSO site where you can print a more detailed map suitable for estimating VY's changing brightness. Maps created with Stellarium

You have plenty of time to see this magnificent star before that happens. First, shoot a line through the belt of Orion towards the east until you come to Sirius. An outstretched fist below Sirius, find a triangle of three easy-to-see stars, then use the detailed map (above) to star-hop your way to VY just as I did. For reference, the “triangle” fits nicely in a the field of view of typical binoculars.

NGC 2362 is one of the finest overlooked clusters in the sky. Credit: NASA

Those with telescopes are in for a treat. If the air is steady and you study VY closely at medium and higher magnifications, you’ll see a very small red-colored nebula around the star.This is material that’s been expelled during the star’s outbursts.

I’ve also included two other “must-sees” on the map — the beautiful, colorful double star h3945 which any scope can split into two and the stunning little cluster surrounding Tau called NGC 2362. See them all and you’ll have a most satisfying night.

Zippy little asteroid 2012 BX34 makes a quick visit

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Funny how linear things are in Orion's Belt and Sword. This 21-minute long time exposure with a 120mm lens shows the trails of the three Belt stars at top and the Sword. The slightly fuzzy trail of the Orion Nebula is the middle stripe near bottom. Photo: Bob King

I had a good night under the stars last night. Temperatures in the 20s made it easy to be outside for a change. It also meant I could make a few time exposures without having to worry about running out of battery power. Winter’s Milky Way is fainter and less textured than the summer version with its chunky star clouds. From a rural site, it slices diagonally from right to left across the southern sky and reminds me of rising smoke from a smouldering campfire. Knowing that it’s jammed with billions of stars thousands of light years thick jazzes my brain every time I see it.

The Milky Way last night around 10 o'clock. Sirius is at bottom; Orion with his 3-starred Belt and Sword dangling below is at right. Details: 15mm lens at f/2.8, ISO 3200 and 30 second exposure. Photo: Bob King

A 36-foot wide asteroid skimmed near Earth at 9:30 a.m. CST this morning passing only 36,750 miles away before zooming back into the deeps at more than 21,000 mph. No danger was ever expected from 2012 BX34, since a rock that size would disintegrate into pieces if it were to strike our atmosphere. At best we might expect a few meteorites. No worries. The asteroid’s path was well known beforehand and any chance of a collision ruled out.

Some amateur astronomers saw and photographed the object, but it was challenge, because 2012 BX34′s tiny size meant it was faint – only about 15th magnitude at best.

Asteroid 2012 BX34 is the faint streak to the right of the top star in this 2-minute time exposure photo taken early this morning. Credit: Ernesto Guido, Giovanni Sostero & Nick Howes

Several asteroids a year come closer to the Earth than the moon’s distance of 240,000 miles. 90% of the larger ones, ranging from mountain-size on up, are already known thanks to detailed surveys with both ground-based and orbiting telescopes. The tally stands at around 910 for the moment. 2012 BX34 ranks 15th on the list of closest approaching asteroids. Below are the top ten as of January 27, 2012 along with their distances at the time of closest approach to Earth:

1. 2011 CQ1 – 3,405 miles on Feb. 4, 2011
2. 2008 TS26 – 3,821 miles Oct. 9, 2008
3. 2004 FU162 – 4,060 miles March 31, 2004
4. 2011 MD – 7,500 miles June 27, 2011
5. 2009 VA – 8,699 miles Nov. 6, 2009
6. 2008 US – 15,534 miles Oct. 20, 2008
7. 2004 YD5 – 20,000 miles Dec. 19, 2004
8. 2010 WA – 24,000 miles Nov. 17, 2010
9. 2011 CF22 – 24,000 miles on Feb. 6, 2011
10. 2008 VM – 29,760 miles on Nov. 3, 2008

The list is interesting because the closest approaches have all been within the past few years. Are we suddenly being buzzed by more asteroids? No. What you’re seeing is a selection effect due to improvements in equipment, cameras and deliberate surveys to hunt for Earth-approaching asteroids that might pose a threat to Earth now or in the distant future. It’s a little like hunting for blueberries in the forest. After you find the first patch and get familiar with the look of the leaves and habit of the plant, you suddenly start seeing blueberries everywhere.

Comet Lovejoy pokes its head above Arizona’s horizon

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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.

Beautiful aurora! What makes it happen?

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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.

Things to see while waiting for the storm to hit

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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

Big solar storm, possible auroras on the way

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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.

Mars shifts gears as it approaches Earth

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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.