Monthly Archives: March 2012

Does it snow microbes on Enceladus? Mars cloud update

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Jets of salty water ice and organic compounds shoot out from fissures or cracks in the ice crust in Enceladus' south polar region. Credit: NASA/JPL-Caltech/Space Science Institute

Lots of interesting things in the news this week. We begin with Saturn’s 313-mile diameter moon Enceladus. Recent close flybys of the moon by the Cassini spacecraft have revealed more than 90 jets spraying water vapor, particles and organic compounds from its south polar regions. The source of these otherworldly geysers is believed to be a huge underground sea. Cracks in Enceladus’ crust of ice allow the warmer water to shoot out and crystallize in the cold vacuum of outer space.

Cassini has flown through the spray and used its ion and “tasted” the watery jets with its neutral ion spectrometer. Besides water and organic materials , the probe has found salt in the ice with the same salinity as that in Earth’s oceans. Add the fact that the temperature in the fissures is more than 200 degrees warmer than the average surface temperature of -330 Fahrenheit, and you begin to wonder if Enceladus might provide a hold for life.

Closeup taken by the Cassini spacecraft of some of the more than 90 geyser-like plumes blasting from Enceladus. Credit: NASA/JPL-Caltech/Space Science Institute

Carolyn Porco, planetary scientist and leader of the Imaging Science team for Cassini, thinks so. “”The kind of ecologies Enceladus might harbor could be like those deep within our own planet. Abundant heat and liquid water are found in Earth’s subterranean volcanic rocks. Organisms in those rocks thrive on hydrogen (produced by reactions between liquid water and hot rocks) and available carbon dioxide and make methane, which gets recycled back into hydrogen. And it’s all done entirely in the absence of sunlight or anything produced by sunlight.”

The deepest point on Earth in the Mariana Trench glows in the lights of Cameron's submarine. Click image to see a video. Credit: National Geographic / Associated Press

You only have to look at deep sea explorer’s James Cameron’s record-breaking solo dive of 35,756 feet to the deeps of the Mariana Trench Monday to know that life thrives in extreme environments. Even in that utterly dark, crushing-pressure and near freezing environment, he saw inch-long shrimp-like arthropods swimming outside the window of his submarine. Protected from the bitter cold and dangerous radiation of space, tiny microbes inside Enceladus might be swimming about just as comfortably.

Deinococcus radiodurans bacteria is one of the toughest organisms known. It can survive extreme cold, vacuum, dehydration and deadly radiation. Could something similar survive or even thrive inside Enceladus or on its icy surface?

Enceladus gets its heat from Saturn. The ringed giant’s powerful gravitational pull on the moon makes it flex one way and then another during its 33-hour long orbit, warming the interior and melting ice to make water. Picture Enceladus as one of those liquid-filled hard candies. For all we know, it could be snowing bacteria on the moon as material from the jets freezes and settles back on the surface.

The bump at upper right is the curious cloud photographed by amateur astronomer Wayne Jaeschke on March 19.

About a week ago I shared amateur astronomer Wayne Jaeschke’s photo of an oddball cloud high above the surface of Mars that looked like a bump along the planet’s edge.

While both water and dry ice clouds are common on Mars, this one seemed unusually high. Everything from a high-altitude dust storm to the plume of an unseen impact were suggested as the cause. Amateurs continued shooting the planet and the pros studied pictures taken by the Mars Reconnaissance Orbiter’s Mars Color Imager. Nothing has turned up yet in the spacecraft images, indicating the cloud was brief-lived. Scientists are still going over pictures taken by Mars Odyssey orbiter’s Thermal Emission Imaging System (THEMIS). Perhaps they’ll find something there.

According to Bruce Cantor, senior staff scientist at Malin Space Science Systems, the phenomenon is most likely a cloud or haze composed of water ice that forms during the early morning hours.

The 8-day moon's crazy with craters. Look for a great concentration of them on the moon's southern half along the day-night border. Credit: Frank Barrett

Tonight the moon’s a day past first quarter in the constellation Gemini the Twins. It’s high in the south at nightfall and beckons anyone with a small telescope to stop and see the craters.

First quarter to gibbous phase is the best and most convenient time to see the hundreds of craters that carve bowls of every size in the lunar landscape. The larger ones have spectacular mountain peaks in their centers formed from material that rebounded upward after the impact. While the planets take time and experience to discern their details, the moon lets it all hang out.

Venus and Pleiades on a beautiful collision course

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Night by night Venus and the Pleiades approach each other until the planet's smack inside the cluster next Wednesday evening April 3. Positions shown for around 9 p.m. CDT. Created with Stellarium

If you enjoyed the dazzle of Jupiter and Venus at dusk recently, get ready for Act II, when Venus passes through the most famous star cluster of all, the Pleiades. Also known as the Seven Sisters cluster, the Pleiades is that little bunch of stars in the shape of a miniature dipper. It’s located in the zodiac constellation Taurus the Bull and sparkles in the western sky at nightfall.

The stars in the Pleiades are named after the seven daughters of Atlas. Dad and mom (Pleione) are also included. Most people can see six with ease. Pleione is more difficult; Celaeno and Asterope are generally not visible. Credit: John Lanoue

Although not as showy as Jupiter and Venus together, rarely does a bright planet passes directly through the sky’s brightest star cluster. The Pleiades represent the seven daughters of Atlas, the Greek god who carried the heavens on his shoulders. Located 425 light years from Earth, the cluster is rich in hot, blue-white stars. Astronomers estimate its age at 100 million years.

Venus inches closer to the sisters night by night until joining them on April 3. That evening the planet will blaze just to the left of cluster’s brightest star Alcyone (al-SYE-oh-nee). Don’t expect Venus to quietly blend in. At magnitude -4.4, it shines more than a thousand times brighter than 3rd magnitude Alcyone.

Brilliant Venus in the Seven Sisters cluster back on April 3, 2004. Photo: Bob King

Over millions of years, the regular and repeating gravitational attraction between Venus and Earth have caused their orbits to reach what astronomers call “near-resonance”. The two planets are now in a comfortable relationship such that for every 8 orbits Earth makes around the sun, Venus completes 13. Seen from Earth, Venus returns to nearly the exact same part of the sky every 8 years.

No matter when you look up at Venus, you’ll see it there again in 8 years. And if you guessed that the last Venus-Pleiades visit occurred in April 2004, you’re right!

I’m curious how many cluster stars will be visible with the naked eye with Venus tucked inside on April 3. The best views will be with binoculars and small, low power telescopes. If you’ve never looked at the Pleiades before with optical aid, you’ll love the view. So many more stars are visible, and with the brightest planet in their midst, get ready for a spectacle.

Introducing a new constellation – Rana Veris the Frog of Spring

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A wood frog, a species common in northeastern Minnesota and often the first ones to call. They sound like quacking ducks. Click photo to hear them. Credit: Leah Perkowski-Sisk / NPS

I heard the first wood frogs chortling across the field last night and couldn’t help but make a stellar association. It was 10 o’clock and Arcturus flickered in the east in the same direction as the pond. Who hasn’t looked at the sky and connected the dots to make a personal constellation? It seemed right to make my own, but instead of using faint stars between the main figures  to create a new pattern – a ploy of 17th and 18th century mapmakers and astronomers – I co-opted a familiar constellation and gave it a new identity.

Rana Veris, a re-purposing of the ancient star group called Bootes the Herdsman. The green frog is a tree frog, another species native to Minnesota. Created with Stellarium. Photo: NFWS

Of course I know this is perfectly silly, but it struck me how Bootes the Herdsman could just as easily be re-visioned as a frog. And to keep everything on the up and up, a fitting name with ancient roots was required. That’s where Latin came in handy. “Frog” in the ancient Roman tongue is “rana” and “ver” or “veris” is spring. Put them together and you’ve got Rana Veris or the Frog of Spring. Notice how the frog’s legs splay out like the stars below Arcturus, and the shape of the head nearly matches the 3-star triangle at the constellation’s north end. Perfect.

I’m not expecting anyone to recognize this old-new constellation, but only to see my use of poetic license as another example of the pattern-seeking species we are. Hey, I’m only human. After all, that’s how the real constellations got there in the first place. They were probably used as an easy way to keep track of cultural stories and myths.

The constellation Gemini the Twins goes back at least to the Babylonians who knew the group as The Great Twins - a reference to Gilgamesh and Enkidu from the Epic of Gilgamesh.

By 4000 B.C. many of present day constellations were already well-established among the Sumerians of the Middle East. They drew their outlines on vases and game pieces. In particular, sky watchers back were very familiar with the stars of the zodiac, the path traveled by the sun, moon and planets. The presence  of this important “heavenly highway” made these stars special. Scorpius, Leo, Taurus and Gemini – some of the oldest – go straight back to Sumeria.

The ancient Greeks recognized 48 constellations named for men, women and animals in their mythology but also borrowed from and shared by other civilizations in the Middle East. The first modern constellations were added in the late 16th century when European sailors explored the far reaches of the globe and saw southern hemisphere stars not visible from their homeland. Dutch navigators Pieter Dirksz Keyser and Frederick de Houtman constructed new constellations like Volans the Flying Fish and Tucana the Toucan to commemorate some of the amazing creatures discovered on their journeys.

Pity that Noctua the Owl never stuck. Hands down he's be the patron bird of amateur astronomers. Once upon a time located near the present-day Libra, this drawing comes from Jamieson's Celestial Atlas.

Astronomers and mapmakers created lots of constellations during this era of discovery to as late as the 19th century. Many didn’t survive. My two favorite obsolete groups are Bufo the Toad (no surprise, eh?) and Noctua the Owl. Bufo was invented in the 18th century by physician John Hill; English amateur astronomer Alexander Jamieson pictured the owl on his 1822 Celestial Atlas.

We ended up with 88 constellations and precisely defined borders courtesy of the International Astronomical Union in 1930. I suppose that means my frog doesn’t stand a chance in the grand scheme of things, but at least I can share him with  you.

Double-double planets and the asteroid that upset the apple cart

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Two wide star-planet doubles decorate the spring sky as you face south around 10:30-11 p.m.. local time. The pairs are separated by about four fists held at arm's length. Maps created with Stellarium

I wanted to share a fun observation with you. Maybe you’ve noticed this too. Right now, Mars and Regulus make an obvious pair of bright “stars” separated by about 5 degrees, but following behind them is yet another star-planet duo – Saturn and Spica in Virgo. They’re also 5 degrees apart. Take a look at this double-double the next time you’re out to make the most of this cool coincidence.

The asteroid 5 Astraea will be right next to the 4th magnitude star Iota Leonis just below the Leo's tail. The map shows the sky facing southeast around 9 o'clock.

While we’re talking spring stars, I got a good look at supernova 2012 aw in the galaxy M95 a couple nights ago. It’s been holding steady at about magnitude 13.1. For those of you who’d like to watch the supernova fade with time, please use the chart at the end of this blog. It has new, accurate magnitudes for stars near the galaxy to help you estimate the changing brightness of the supernova.

Not far from the supernova, those with small telescopes or large binoculars can spot the asteroid 5 Astraea (ASS-tree-uh). The “5″ means it was the 5th asteroid to be discovered and have its orbit determined. Right now, it’s relatively bright at magnitude 9.5 and very near the naked eye star Iota in Leo, making it an easy target in any telescope.

Astraea is 74 miles in diameter and circles the sun every 4.13 years. Unlike the near-Earth asteroids, it orbits a comfortable distance from our planet in the asteroid belt between Mars and Jupiter.

You can use this closeup map to zero in on Astraea. The dates show its position near Iota every five days. The asteroid will look exactly like a star. North is up and stars are shown to about 10th magnitude.

Closest approach to Earth is just 100 million miles; this week it’s 112 million miles away. The first four asteroids – Ceres, Pallas, Juno and Vesta – were all discovered between 1801 and 1807. After that, astronomers looked in vain for 38 years until the 5th – Astraea – was spotted on December 8, 1845 by German amateur astronomer Karl L. Hencke.

Size comparisons of the first 10 asteroids discovered. The gray circle represents the moon. Credit: Vystrix Nexoth with my own additions

After so many years, some astronomers thought that four was all she wrote, but Hencke mustered on, as amateurs still do to this day, and found #5 after 15 years of effort. Funny – he stumbled on Astraea while looking for Vesta one night. Hencke went on to discover 6 Hebe just 2 1/2 years later. Asteroid 2005 Hencke is named in his honor.

Astraea’s discovery was pivotal because it was the start of a great flood of asteroid discoveries that challenged the prevailing view that Ceres, Pallas, Vesta and Juno were planets. 19th century astronomers soon realized they were dealing with an entirely new beast. And beast it is. Today, as of December 2011, there are 310,376 numbered asteroids. The beat goes on!

This map/sketch of M95 and the supernova includes stars with magnitudes taken directly from a chart by the American Assn. of Variable Star Observers (AAVSO). Use it help you estimate 2012 aw's brightness. View shows the sky at about 100x. Illustration: Bob King

Northern lights possible tonight March 27-28

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Just a quick note that the Kp index is up to “4″ as of 11 p.m. CDT and the auroral oval is creeping like a green amoeba toward the northern border states tonight March 27-28. Be on the lookout for auroras low in the northern sky. We’re overcast in Duluth, Minn. so no sightings here. A favorably positioned solar coronal hole is the cause for the uptick. More activity is also likely Wednesday night the 28th.

Buckle up for the cosmic roller coaster ride of your life

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Water creates a chaos of shapes as it splatters into the air after striking a rock in a nearby creek. Photo: Bob King

Last week I watched water racing down a creek slam up against a boulder and break into a frothy spray of droplets and blobs.  My eyes struggled  to make sense of it. The camera proved a far better instrument to dissect the spray into a series of moments, so I could better appreciate the water’s ephemeral shapes and patterns.

We can stop movement and hold time still for a moment, but that’s all. You and I and everything around us are in constant motion. Take the rotation of the Earth. As I type, my keyboard, home, and the entire city of Duluth, Minn. are all moving together at 708 miles per hour toward the east. Speed varies according to latitude, ranging from 0 mph at the poles to 1,041 at the equator. Folks in Nome, Alaska are traveling at 455 mph on the merry-go-round, while those in Los Angeles zip along at 860 mph.

Depending on your latitude, the speed with which your rotation speed varies. Close to the poles, it's slow because you turn through a very tiny circle in 24 hours. At the equator, you have travel the entire circumference of the Earth in the same time. Illustration: Bob King

The reason rockets are launched in Florida and not North Dakota is because Florida is closer to the equator, giving them a 250 mph edge compared to Fargo as they head into orbit.

To determine how fast you’re moving, multiply Earth’s circumference times the cosine of your latitude and divide by 24 hours like this: 24,902 mph x cos (latitude) / 24 hours. Cosines are easily found by heading over to the handy Cosine Calculator and keying in your latitude. With that number in hand, use your computer’s calculator to arrive at your personal velocity.

We travel nearly 67,000 miles per hour in our yearly orbit around the sun. Illustration: Bob King

Spinning is just one of Earth’s several motions. We’re also orbiting the sun at 18.5 miles per second or nearly 67,000 miles per hour. At that speed our planet traverses 600 million miles in one year. Since Earth’s about 8,000 miles in diameter, it moves about 202 times its own size in one day. Even sitting still we’re putting on miles at a fantastic rate. Live till you’re 80 years old and you’ll  have 48 billion frequent orbital-flyer miles to show for it.

Destination Vega! The sun and solar system are moving the general direction of the bright star Vega in the constellation Lyra. Photo: Bob King

So far we’ve only talked about Earth, but the sun isn’t standing still either. Our star is one of several hundred billion stars in the Milky Way galaxy, all of which are moving. Based on studies of the motions of stars in our neighborhood, astronomers have determined that the sun hauls it family of planets, comets and asteroids at 43,000 miles per hour in roughly the direction of the bright star Vega in Lyra.

In the course of a  lifetime we will have moved 40 billion miles closer to the star. Unfortunately that huge figure will hardly begin to close the gap between the two stars. Vega is not only 25 light years away (150 trillion miles), but it’s not standing still either. If you’d like to see where we’re headed, face northeast around 11 o’clock the next clear night. The bright, twinkling star low in the sky is Vega.

The sun circles the galactic center once about every 225 million years traveling at 483,000 mph. Illustration: ESO with additions

If you guessed that we’re not quite finished yet, you’re right. The Milky Way is a gigantic starry pinwheel, where the speeds of stars vary with distance from its center the same as the speed of a planet varies with its distance from the sun. The spinning of the galaxy carries the sun and neighboring stars around the galactic center at 483,000 mph or nearly 7 times faster than Earth orbits the sun.

Good thing the sun is holding onto us or we’d soon be lost among the stars like change dropped from a pocket. Our solar system is located about 2/3 the way from galaxy’s center to its edge and takes 225 million years to complete one orbit. Each year we celebrate our birthday after completing another cycle around the sun. Since the sun and planets first formed 4.6 billion years ago, the sun has orbited the galactic center 20 times, making it 20 galactic years old. Hey, that means in another 225 million years it will finally come of age!

Watch out for what the future brings - Andromeda and the Milky Way will one day be one galaxy sometimes referred to as "Milkomeda". Other members of the Local Group are labeled. Credit: Andrew Colvin

The Milky Way is one of more than 50 galaxies in a small cluster of galaxies called the Local Group. Ours and the Andromeda Galaxy, located 2.5 million light years away in the constellation Andromeda, are the group’s two biggest members. As if we weren’t moving in enough ways, these two galactic behemoths are hurtling toward one another at 50 miles per second or 270,000 mph.

2.5 billion years from now we’ll collide in a spectacular display of fireworks as merging gas clouds fire up brand new clusters of stars. Over time, the two spiral galaxies will evolve into one much larger elliptical galaxy some like to call “Milkomeda” (milk-AH-meh-duh).

The Local Group is one of many galaxy clusters belonging to one vast assemblage of clusters named the Virgo Supercluster centered in the constellation Virgo. Credit: Andrew Colvin

The Local Group is a small cluster on the outskirts of the much larger Virgo Supercluster of galaxies. Consider Virgo as downtown New York and our gang as a small town in the boondocks. Like my daughters, who are drawn to the dazzle and glitter of the big city, the Local Group is falling at more than half a million miles an hour toward the center of the Supercluster.

Still not dizzy yet? Let’s take one final step and put the pedal to the metal.

Relative to the cosmic background radiation – the ever-expanding , steadily cooling energy left over from the Big Bang that permeates all of space – the Milky Way galaxy is moving at the amazing rate of 1.3 million miles per hour roughly in the direction of Leo and Virgo. The reason for our great haste? New space created between the galaxies as the universe expands causes them to appear to rush apart from each other. The Local Group holds together through the combined gravitation attraction of its members, but when you take in the bigger scene, galaxies have been rushing away from each other at alarming speeds since the Big Bang 13.75 billion years ago.

OK, even I need a little help at this point, so let’s sum up:

* We’re rotating around 700-800 mph depending on latitude.
* Orbiting the sun at 67,000 mph
* Traveling among the nearby stars at 43,000 mph
* Orbiting the center of the Milky Way at 483,000 mph
* Moving toward Andromeda at 270,000 mph
* Diving into the core of the Virgo Supercluster at 540,000 mph
* Riding aboard the Milky Way in the expanding universe at 1,300,000 mph

And yet, in spite of all the whirl and flow, we can still find quiet moments under a dark sky to contemplate it all.

A portion of the Hubble Deep Field photograph showing a multitude of galaxies. The space between each galaxy grows larger with time as the universe continues its expansive ways since the Big Bang about 14 billion years ago. Credit: NASA/ESA

A painting in the western sky

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Tonight's gathering of Moon, Jupiter, Venus and transcontinental airliner in the western sky in mid-twilight Sunday. Details: 35mm lens at f/4.5, ISO 400 and 6 seconds. Photo: Bob King

I hope you had a chance to see the spectacle of moon and planets in the western sky Sunday evening. The full circle of the moon is visible alongside Jupiter. The bright part of the circle (crescent) is illuminated by the sun, while the remainder of the moon shines by sunlight reflected from Earth’s clouds, water and land. Earthshine is much fainter than direct sunlight, which is why that portion of the moon glows only weakly.

Not far above the pair is Venus and the Seven Sisters star cluster. Very eye-catching all!

Tonight the moon will be next to Venus and even closer than it is to Jupiter tonight, but you don’t have to wait till dusk to see the pair. Why not try and spot them in binoculars before sunset?

See if you can spot Venus in the daytime today using the moon as your guide. All you need is a pair of binoculars. If your sky's really clear, Venus will be visible with the naked eye. Time shown is CDT. Created with Stellarium

The moon is fairly easy to see in a clear sky by late afternoon and early evening. Once you find it, take a look through binoculars and you’ll have no problem seeing Venus not far to its upper right. Seeing Venus in a sunlit sky can be challenging, but with the moon nearby you’ve got the cosmos on your side. Give it a try. I think you’ll be surprised how easy it is. And once you’ve spotted the duo in binoculars, take the next step and try to pick out Venus with your naked eye.

The maps show the pair for the central U.S. If you live on the East Coast, Venus will be a tad higher to the right; for the West Coast they’ll be more “level” or in line with each other.

Excellent cloud details show up in this photo of Venus taken on March 24, 2012. Credit: George Tarsoudis

George Tarsoudis of Greece took a wonderful image of Venus that shows far more detail than what you’d see with your eyes through any telescope. Using a digital camera and ultraviolet filters on his 10-inch scope, he captured textures in the planet’s clouds not visible in everyday “visual” light.

Even to the most seasoned observers rarely see detail in Venus’ clouds due to their extremely low contrast. His photo reminds me of the images taken by the Pioneer Venus Orbiter spacecraft in 1979.

Weekend sky show features moon and planets; space station dodges debris

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The moon passes by Jupiter and Venus over the next three nights. Look west 45 minutes to an hour after sunset. Created with Stellarium

Yesterday was only a tease to the nice planet-moon alignments happening over the next few nights. Tonight (Saturday) the moon will be higher in the west nearer Jupiter, but Sunday and Monday will bring the best pairings. Hope for clear skies and don’t forget binoculars. Crescent phase is ideal for seeing the the pale blue-gray earthshine that dimly illuminates the remainder of the moon beyond the crescent.

For morning observers, the International Space Station (ISS) makes bright passes all week long. A typical one lasts 4-5 minutes with the ISS moving from west to east across the sky. The times below are for the Duluth, Minn. region.

For times for your town, please log on to Heavens Above or go to Spaceweather’s Satellite Flybys and enter your zip code.

* Sun. March 25 beginning at 5:59 a.m. Bright pass across the northern sky.
* Mon. March 26 at 5:04 a.m. Exits Earth’s shadow east of the Big Dipper bowl and continues across the north.
* Tues. March 27 at 5:41 a.m. across the north
* Weds. March 28  at 6:19 a.m. ”     ”
* Thurs. March 29 at 5:23 a.m. ”     ”
* Fri. March 30 at 6 a.m. ”     ”
* Sat. March 31  at 5:05 a.m.  ”     ”

Controlled by teams on the ground, the Robonaut 2 humanoid robot holds an instrument to measure air velocity during a system check in the Destiny laboratory of the space station recently. Click photo to learn more about the robot. Credit: NASA

Earlier this morning, the crew of the space station had to take shelter in the Russian Soyuz spacecraft after their flight director determined there was a small chance the station would be hit by a fragment of a Russian Cosmos satellite. The debris passed by without incident about 9 miles from the station at 2:38 a.m. this morning.

It’s the third time in the history of the space station astronauts have had to take shelter from incoming space junk. The incident highlights the growing danger to satellites and the space station from man-made orbital debris. The station is designed to handle hits from objects around 1/2 inch (1 cm) or smaller without significant damage. Anything larger can spell trouble.

The United States Space Surveillance Network currently tracks some 8,000 man-made objects of baseball size or larger. Most of the debris orbits around 500 miles high – well beyond the ISS –  with a small amount in the space station’s orbital zone. The junk is comprised of active and inactive satellites, spent rocket bodies, fragments and the remains of a satellite collision. Small pieces wouldn’t be a big issue except they’re moving at over 17,000 mph and pack a wallop.


NASA video explains how the recent solar storms have directly affected Earth 

In a related story,  the recent pounding the Earth took from a series of flares from sunspot region 1429 in the last few weeks not only provided light shows for northern sky watchers but also heated the planet’s upper atmosphere.

“This was the biggest dose of heat we’ve received from a solar storm since 2005,” says Martin Mlynczak of NASA Langley Research Center.  “It was a big event, and shows how solar activity can directly affect our planet.” The extra heat caused the upper atmosphere to puff out, increasing the drag on satellites and satellite debris. While that’s not healthy for functioning satellites, the increased drag performs a useful cleaning function by lowering the orbits of the debris. This shortens their lifetime in orbit,  speeding up re-entry and burn-up.

As for the rest of the heat, most of it was re-radiated back into space thanks to carbon dioxide (CO2) and nitric oxide (NO) which act as natural coolants to bring the upper air temperature back into equilibrium. Check out the full story HERE.

See a razor moon tonight plus how we solved a dark star mystery

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A 90-minute exposure of M95 with 2012 aw marked taken through a 16-inch telescope. Credit: John Chumack

First, an update on supernova 2012 aw in M95. A group of astronomers have gone back over older photos of the galaxy and identified the star before it went supernova as a red supergiant about 8 times more massive than the sun. This would make it one of the reddest and coolest of its class to become a supernova. Or the star was shrouded in a dust cloud of its own making. A third possibility is that it’s been heavily reddened by dust within the galaxy. I’ll go out on a limb and suggest this might explain why 2012 aw hasn’t continued to brighten beyond 13th magnitude.

Find a place with an open horizon to the west to spot a super-thin crescent moon at dusk. This map shows the sky facing west 30 minutes after sunset. Maps created with Stellarium

Not all of us have dark skies and a telescope big enough to see a supernova, but if you have clear skies tonight, it shouldn’t be too hard to spot a wiry crescent moon. Look well below Venus and Jupiter in the western sky a half hour after sunset. The shaving of moon will be less than a day and a half old. In the coming nights it will glide by the bright planets, becoming easier to see as it moves up and away from the sun.

Once the sky is dark, let your gaze drift upward from Jupiter and Venus. The first object you’ll see is the little clump of stars called the Seven Sisters or Pleiades. It’s about as high above Venus as Venus is above Jupiter. Venus will have a meet-and-greet with the cluster early next month. Watch them get closer each night.

The pentagonal Auriga stands above Aldebaran in Taurus the Bull and the bright planets Jupiter and Venus in the west at nightfall in late March.

Straight up from the Seven Sisters you’ll run into the bright star Capella, the alpha star in the constellation of Auriga the Charioteer. Spring is my favorite time of year for Auriga viewing because the five-sided figure stands up like a house in the western sky. The three stars across the top, including Capella, form the roof, while several others outline the two sides and floor.

Strictly speaking, the lower left star in Auriga officially belongs to Taurus but tradition allows both star groups to share the star to better complete their figures. Sounds like a good marriage to me.

Just below Capella, a name meaning “she-goat” and a reference to the goat that suckled Zeus as a child, is a compact triangle of stars. Capella bore two baby goats or kids represented by the two bottom stars in the triangle. The other star – Epsilon Aurigae – marks the charioteer’s left elbow.

The Kids and Epsilon are just below bright Capella.

Epsilon is one of the most intriguing stars in the sky. It’s normally brighter than the Kids, but every 27 years for about 18 months it’s eclipsed by a dark companion object and fades to become the faintest of the trio.

The most recent eclipse wrapped up last year.  Professional astronomers, working with large Earth and space-based telescopes like the Hubble and Spitzer, along with a small army of dedicated amateur astronomers, carefully studied every aspect of the eclipse and finally solved the mystery of the dark object and learned more details about Epsilon itself.

Artist's concept of the dark disk with a hot star at center. Every 27 years the disk passes in front of Epsilon (right) and dims its light for about 18 months. When the disk has orbited out of our line of sight, Epsilon returns to its normal brightness. The system is about 2,000 light years from Earth. Credit: NASA/JPL-CalTech

The thing doing the eclipsing is a dark disk of gas, dust and gravel-like rocks some seven times larger than the distance between the Earth and sun. At its center is a blazingly hot, blue-white star hidden from view by the dust. The Spitzer scope, which picked up hints of the “invisible” star in infrared light, finally helped us understand what held the disk together – a single star . The star and disk orbit Epsilon, which is brighter and several times more massive than the sun. Epsilon is the star you see with your naked eye.

As to how the disk got up there, that’s still unclear, but it’s possible there are planets inside like raisins in a bagel ring. Because the two orbit so closely, perhaps the disk star pulled material from Epsilon into a disk. Already scientists are coming up with ways to press this star system for more secrets when the next eclipse begins in 2036.

Amateur astronomer photographs curious cloud on Mars

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The little bump at upper right on the planet is the cloud or plume photographed Monday night March 19, 2012. It's located in the planet's southern hemisphere. Credit: Wayne Jaeschke

An amateur astronomer in West Chester, Penn. took a picture of a curious Martian cloud several nights ago that has the community of Mars observers abuzz. Wayne Jaeschke photographed Mars on the evening of March 19 with a 14-inch telescope and noticed the plume after processing his images.

It struck him as odd the way it stood so high off the planet’s limb, so he shared it with other Mars watchers in the online Mars Group. He also made a cool 5-frame animation of the feature you can view HERE.

Once word got out, confirmation of the cloud came in from other amateur astronomers who had photographed it both before and after the 19th. No one is certain of the cloud’s nature yet, but it could be made of ice crystals or perhaps even dust whirled into the Martian atmosphere. Its altitude is estimated at 60 miles or higher. See more photos HERE.

Mars photographed by Hubble in March 1997. The left image is a full-color view; the right was taken through a blue filter to emphasize the clouds. Most Martian clouds are found in the equatorial and polar regions. Polar clouds are widespread during the Martian fall and winter. Credit: NASA/ESA

Mars is no stranger to clouds, though not the puffy cumulus or heavy rolls of stratus we’re familiar with on the home planet. Mars’ atmosphere is composed mostly of carbon dioxide and extremely thin. You’d have to jump in a spy plane and travel to an altitude of 115,000 feet (21.7 miles) in Earth’s atmosphere to approach the rarity of Martian air.

That doesn’t stop Mars from having clouds. Seasonal carbon dioxide and water ice vaporizing from the Martian polar caps provide the necessary materials to build clouds, and the atmosphere is sown with the dust to seed their formation.

Cirrus clouds are composed of ice crystals like the clouds on Mars. Photo: Bob King

Some clouds are made of water ice, like the familiar afternoon clouds that form around the planet’s high elevation extinct volcanoes like Olympus Mons, while others are composed of dry ice crystals. They’re mostly wispy, much like the ice crystal clouds called cirrus or “mares’ tails”, and they drift across the planet’s pink sky. They’re propelled by winds just like Earth’s clouds.

When Mars experiences strong dust storms, orange clouds of dust billow up above its surface that are easily visible in mid-sized telescopes. Occasionally these clouds can become so widespread that they literally blanket the planet, blocking its surface from view for a time.

The small protrusion extending into the night sky of Mars in this 1997 Hubble photo is probably a high cloud catching sunlight. Credit: NASA/ESA

This wouldn’t be the first time a cloud reached high enough to catch the sunlight and stand out above Mars. Back on May 17, 1997, the Hubble Space Telescope photographed something similar poking beyond the Martian terminator (border between day and night).

In the photo at right, the other white patches along the left side of the planet are additional clouds and hazes.

No one to my knowledge has seen the new cloud visually yet, but observers have been and will be seeking it out in the coming nights. The plume appears to be a very low contrast feature, requiring excellent observing skills, a fair-sized telescope and good optics.

Martian cirrus-type clouds photographed by the Sojourner rover. Credit: NASA

If you’d like to make an attempt, it’s located just south of the dark feature Mare Cimmerium at Martian latitude 44 degrees S, 190 E. I’ll update with new photos in the coming days provided the cloud’s still there. Perhaps NASA will even get a picture of it with the orbiting Mars Reconnaissance Orbiter. Speaking of which, here’s a recent photo taken by the spacecraft of thin clouds over ice-covered dunes. Should we ever establish a base on the planet in the future, there will definitely be a need for a Martian meteorologist.

Bright, ice-covered dunes and winter ice protected in shallow grooves on the ground are visible through clouds in Mars' southern hemisphere recently. Click to enlarge. Credit: NASA/JPL/University of Arizona