Smiles all around as meteorite hits comet

One of the newest extraterrestrial visitors to land on Earth (at left), an 88 gram meteorite that fell near Paris late this summer. The photo at right shows meteorite collector Alain Carion with Mr. Mosset and Miss Comette. Credit: Alain Carion

OK,  now that I’ve drawn you in to this story, here’s the truth. The meteorite didn’t hit exactly hit a comet but rather a ‘Comette’ as in the roof of a home owned by Madmoiselle Comette (pronounced the same) and her companion Monsieur Mosset in Draveil, a suburb of Paris. No one’s quite sure when the meteorite punctured the roof, but it may have happened in August while the couple was on vacation away from the city.

In early September their roof was leaking after a thunderstorm, so they called a roofer to make the repair. While replacing the roofing tiles, he discovered a curious black stone with a pale gray interior and presented it to the owners. Suspecting it might be a meteorite, Mosset later took the stone to the French meteorite collector Alain Carion who owns the Minerals-Fossils-Meteorites shop along the banks of the Seine River in Paris. Carion’s face must have lit up in a big smile, because it was clear to him that the 88g (3 ounces) specimen was indeed a rock from space.

A 5.3 kilogram (11.6 lbs.) new specimen of the Draveil meteorite. Credit: Alain Carion/Impactika.com

In his own words: “Mr. Mosset did show me a splendid extra-terrestrial rock of 88 grams, with all the right features: black fusion crust, regmaglypts , pale matrix inside with traces of iron and troilite, attracted to a magnet. Perfect! We had here a real meteorite, and fallen just outside Paris.” Just an FYI, regmaglypts are those thumbprint shaped depressions seen in some meteorites. They’re places where the heat of entering Earth’s atmosphere has melted out softer materials in the stone.

To the delight of everyone, two additional pieces weighing around 2 and 5.3 kilograms  of the meteorite fall have recently been found. Since no known meteorite has ever fallen so near Paris, meteorite collectors around the world are very excited about the possibility of adding a small fragment of history to their collections. From outward appearances, the meteorite looks like an what’s known as an ordinary chondrite. Chondrites are extremely ancient – 4.5 billion years old – and thought to originate in the crusts of asteroids in the asteroid belt. Collisions between asteroids liberate fragments which eventually find their way to Earth and lovely places like Paris.

This week the International Space Station (ISS) begins making passes over the region during the early evening hours. Here are times when you can see it fly over the Duluth, Minn. region. For times for your town, head over to Spaceweather’s Satellite flybys and ener your zip code or log on to Heavens Above. The ISS will appear as a brilliant star moving from west to east. And who knows. Maybe a meteorite will hit your roof too while you’re out with your head in the sky.

* Tonight October 17 starting at 7:52 p.m. Brilliant pass across the southern sky. Disappears into Earth’s shadow just east of Altair near the bottom of the Summer Triangle. * Tuesday October 18 at 6:54 p.m. low in the south and southeast.
* Wednesday October 19 at 7:31 p.m. About as bright as they come. High pass in the southern sky and brighter than Jupiter.
* Thursday October 20 you get two for the price of one. First pass at 6:33 p.m. across the south; 2nd brief pass in the northwest at 8:08 p.m.
* Friday October 21 at 7:10 p.m. Brilliant as it travels nearly directly overhead

Creepy crawlies aboard mission to Mars’ moon Phobos

Phobos, the destination of the Russian Phobos-Grunt mission, is seen here in orbit about Mars through the eyes of the Mars Express orbiter. The moon is only 14 miles across and orbits the planet in just over 11 hours or twice during each Martian day of 24 hours 37 minutes. Click to enlarge. Credit: G. Neukum (FU Berlin) et al., Mars Express, DLR, ESA

The Russians will soon return to Mars with the launch of the Phobos-Grunt probe on or around November 8. Russia hasn’t had a successful interplanetary mission in decades. The last attempt was the Mars 96 probe launched in 1996 which quickly ended when a rocket engine failed while still in Earth orbit. We hope all goes well on this multifaceted and imaginative mission.

The Phobos-Grunt probe being prepared for vacuum chamber testing. Credit: NITs RKP

Phobos-Grunt (‘grunt’ is Russian for ‘soil’ or ‘dirt’) is an unmanned mission of the Russian Federal Space Agency that will land on the Martian moon Phobos and return a soil sample to Earth. This is the first-ever attempt to sample a planetary moon. Assuming a successful liftoff, the probe will reach Mars next October and dispatch the Yinghuo-1 Chinese satellite to orbit and study the planet’s surface. Over the next several months, Phobos-Grunt will study Mars, the Martian moons and search for a safe landing spot as it slowly pulls up alongside Phobos. Touchdown is scheduled for sometime in February 2013.

15 instruments will study the little moon and a robotic arm and drill will gather up soil samples.  Liftoff  from the moon happens in early 2014. The return capsule, expected to arrive back on Earth later that August, will contain 200 grams (just under 1/2 lb.) of soil and include a life science experiment of The Planetary Society, called Living Interplanetary Flight Experiment, or LIFE.

Tardigrades are found everywhere on Earth and have survival skills that would put humans to shame. A sample of them is headed for a round-trip journey to Mars moon Phobos.

The special ‘bio-module’ will hold representatives from all three major domains of earthly life to find out how well they survived for several years in the extremes of outer space. Among the 10 creatures included will be four types of bacteria, three bacteria-like organisms called archaea that thrive in extreme conditions and three species from the domain of eukaryotes or organisms with more complicated cell structures. You and I belong to this last group. Standing in for us will be a fungus (yeast), seeds from the mouse-ear cress plant and my personal favorite – tardigrades or ‘water bears’. These microscopic animals with 8 legs only grow to about a millimeter and are found all over the planet. They’re able to survive in temperatures ranging from near absolute zero (459 below) to 300 above, can handle far more radiation than most animals and live up to 10 years without water. That’s one tough bug!

Phobos is pocked with craters including one very large one named Stickney (far right edge) that nearly shattered the moon. Credit: NASA

Phobos is a fascinating moon. It’s only 14 miles across and orbits 5,827 miles above the surface of Mars. That’s close enough for its orbital motion to outpace the slower rotation of Mars (24 hours 37 minutes) making the moon rise in the west and set in the east in just 4 hours and 15 minutes as seen from the Martian surface.

Based on its density and how the moon absorbs and reflects sunlight, astronomers have determined it’s composed of a mix of rock and ice with the ice locked somewhere below the surface. Its composition matches a group of dark carbon and water-rich meteorites called carbonaceous (car-bon-NAY-shuss) chondrites (KON-drites). Since similar carbonaceous asteroids are known to inhabit the asteroid belt, it’s believed Phobos as well as the smaller Martian moon Deimos were stray asteroids captured by Mars long ago.

Tears for Comet Elenin, but there’s more to life

Seven sunspot groups dot the sun's face in this photo from 8:30 CDT this morning. Credit: NASA/SDO

Time to catch up on the news. The sun is positively peppered with sunspot groups but they’ve been mostly well-behaved with few flares to shows for so much spottiness. Just the same, there’s a good chance for minor auroras across the northern U.S. and Canada this evening from something else in the sun’s bag of tricks – a coronal hole.

Look low along the northern horizon for a greenish glow during the early evening hours . Views will be compromised after about 9 p.m. when the moon is up high enough to spill light across the sky.

Let’s not forget the supernova in the Pinwheel Galaxy in the Handle of the Big Dipper. At magnitude 11.7, it’s still within easy range of 6-inch and larger telescopes. Amazing to think that the supernova, discovered on August 24, is nearly two months “old” and continues to blaze so brightly. Catch it as early as you can at the end of evening twilight before it drops below the trees and roofs. Maps for finding it are here in this earlier blog.

Photo of Comet Elenin's position on October 9 taken through a 10-inch telescope. Stars (long streaks) as faint as 17th magnitude are visible while the red squares are positions of even fainter asteroids in the field of view. No comet cloud or fragments are visible. Click photo to read and see more Elenin attempts. Credit: Ernesto Guido, Giovanni Sostero and Nick Howes

There’s a discussion going on right now among comet observers about whether Comet Elenin is visible or not. Tomorrow, what’s left of the comet makes its closest approach to Earth at 22 million miles. This was the time we’d all been hoping to see it near naked eye brightness, but it crumbled in August and the remaining icy fragments have all but vaporized away in the sun’s heat.

Comet Garradd photographed last night from Italy by ace astrophotographer Rolando Ligustri. Two tails are visible - a blue ion tail at top and a yellowish dust tail below.

Two positive observations of Elenin were made about a week ago by trustworthy observers under excellent skies, but larger telescopes and long time exposures have shown nothing. Other experienced visual observers have also had no success. Granted, they were all battling low altitude and the glow of the zodiacal light. What the two observers would have seen was the faint, residual dust cloud left in the wake of the breakup. The next opportunity to see Comet Elenin will be in about a week, when it will be much better placed in a dark morning sky. Expect lots of amateur astronomers to be out with scopes and cameras for one last attempt. I’ll have more news then.

To find Comet Garradd with binoculars or telescope, face due west and find the two bright stars on the right side of the Summer Triangle - Altair and Vega. Use them to create another triangle with 2nd magnitude Alpha Ophiuchi directly below. Once there, use the map below to navigate the short distance from Alpha to the comet. Created with Stellarium

Despite Elenin’s poor showing, there’s no need to hang your head. Comet Garradd is still going strong at around magnitude 7.5 during the early evening high in the western sky near the border of the constellations Hercules and Ophiuchus (oh-fee-YOU-cuss). From a dark sky it looks like a small, fuzzy puff in binoculars. Telescopes will show a bright comet head or coma and faint tail pointing east. The moon is now rising late enough to provide the dark sky you’ll need for the best view.

Once you're at Alpha Oph, you can star hop up a chain of 5-6 magnitude stars to get to the comet. Nearby Alpha Herculis is also a helpful guide star. This map shows the sky as you face west. Comet positions are shown every five days. The dashed line is the constellation boundary. Created with Chris Marriott's SkyMap software

Don’t forget to look for the X-ray telescope ROSAT tonight we talked about yesterday. Now that its orbit is dropping lower, the doomed satellite has been reported as bright as 1st magnitude! Scroll down to Friday’s blog for links on how to find it.

This image of the asteroid Vesta, calculated from a shape model and based on photos, shows a low angle view of the south polar region. The mountain in the foreground is 13 miles high. Click to enlarge. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

And finally, I’ll leave you with a couple recent pictures taken by the Dawn spacecraft of a dark-rayed crater and one of the highest mountains in the solar system.These wonders of nature are found 168.5 million miles from your doorstep on the asteroid Vesta.

A fresh 1-mile diameter crater surrounded by dark rays of excavated rock from Vesta's crust. Rays are normally composed of bright material, so more study will be needed to answer why these are dark. Click to enlarge. Credit: NASA

Another one bites the dust – ROSAT satellite coming down soon

Jupiter and the waning gibbous moon shine between fall trees late last night. Photo: Bob King

Darkness comes early in mid-October. For some, the disappearance of daylight is tough to handle. We feel like moles in a dark tunnel from dinnertime until the next morning’s breakfast. Most people seem to be more in tune with daylight instead of darkness, yet many sky watchers have learned to embrace the night. The stars may be dim but getting to know them and the ragtag galaxies, planets and nebulae is like being in a room with a thousand candles. Their light and energy stimulate a reflective and peaceful state of mind as satisfying in its way as streaming rays of sunshine. As daylight trickles away, I hope you’ll also find light and inspiration in the nights ahead.

Artist view of the German X-ray observatory ROSAT in space. Credit: German Aerospace Center

Looks like we’re in for Satellite Crash Act II. The German science observatory ROSAT, short for Roentgen Satellite, make its fiery plunge to Earth sometime between October 22-24 over a broad zone between latitudes 53 degrees north and south. Like the widely-publicized burn-up of NASA’s Upper Atmosphere Research Satellite (UARS), this satellite will also come down uncontrolled. Satellite trackers will only have a general idea of where it might land hours before it does. As with UARS, you shouldn’t be too worried. Since the Earth is 2/3 covered in water and thankfully still  blessed with a lot of uninhabited land, there’s a good chance it will crash without incident just as UARS did over the South Pacific.

When ROSAT finally does come down, it will be traveling at nearly 17,000 mph. The tremendous heat generated by friction with the air will burn up much of it up, but German scientists estimate 30 pieces will survive. Unlike UARS, ROSAT’s made of specially hardened components, so more of it will remain intact during re-entry – 3,750 lbs. of pieces will shower the ground versus an estimated 1,200 lbs for UARS. There’s  a 1 in 2,000 chance a person will be struck by the debris, which breaks down to a 1 in 14 trillion chance any particular individual will be hit.

An X-ray emitting neutron star (upper left) blinks out as the moon passes in front of it in these photos made by ROSAT. High-energy X-rays are shown in yellow, low energy ones in red. The moon scatters X-rays given off by the sun. Credit: ROSAT, MPE, NASA

ROSAT, an orbiting space telescope optimized to study the sky in X-ray light, is named after William Roentgen, the German scientist who discovered X-rays back in 1895. It operated for over 8 years beginning in 1990 before being shut down in 1999. Many high-energy objects in the universe emit X-rays including neutron stars, black holes, galaxy clusters and debris blasted into space by supernovas called supernova remnants. Since Earth’s atmosphere absorbs X-rays, telescopes made to focus this powerfully energetic light need to be lofted into orbit.

ROSAT created a detailed (for its time) map of the X-ray sky, took the first photos of X-rays bouncing off the moon and discovered X-ray emission in comets. It’s since been superseded by the Chandra X-ray Observatory with its much finer resolution.

This composite view of the entire sky in X-rays was made by ROSAT. The red is radiation emitted by hot gas in the halo of the Milky Way, the yellow from nearby gas bubbles at several millions of degrees and the highest energy blue from supernova remnants. Credit: ROSAT

You can still watch ROSAT track across your sky in the coming week before its plummet. Below are times when it’s visible from the Duluth, Minn. region. For times for your neighborhood, log on to Heavens Above and select your city and then click the ROSAT link. You’ll be shown a list of passes. When you click the date link, a nifty map pops up to help you know exactly where to look. You can also enter your zip code at the Spaceweather Flyby link and get times and general directions.

Like the space station, ROSAT travels from west to east across the sky, but it’s not nearly as bright. Expect to see a steady moving “star” of about 2nd magnitude or similar in brightness to those in the Big Dipper. It zips along fairly quickly now that its orbital altitude has been dropping from friction with the upper atmosphere.

* Tonight Oct. 14 beginning at 7:55 p.m. A brief and faint (magnitude 4) appearance low in the northwestern sky in the Big Dipper.
* Saturday Oct. 15 at 7:41 p.m. A better and brighter show tonight at mag. 2 1/2. Appears in the northwest and moves through the Big Dipper before fading away under the North Star.
* Sunday Oct. 16 at 7:25 p.m. Excellent high pass in the north at mag. 2.2
* Monday Oct. 17 at 7:08 p.m. Similar pass to yesterday. Bright at mag. 2.0

Crazy Uranus knocked silly by a one-two punch

Uranus and its faint ring system are seen in this composite image by the 10-meter Keck Telescope at near infrared wavelengths. Credit: Lawrence Sromovsky, Univ. of Wisconsin-Madison /Keck Observatory

Uranus is certainly a weird planet. Beneath its atmosphere of hydrogen and helium tinted aqua by clouds of methane lies a thick layer of water, ammonia and methane ices. At the bottom of it all is a rocky core estimated at half the size of Earth. We might picture it as a jawbreaker floating in a big slushy wrapped in blue mist. But that’s not all.

The planet, four times the size of Earth and nearly 2 billion miles from the sun, is tipped on its side to the tune of 98 degrees. For comparison, Earth’s axis is angled just 23.5 degrees so we – and all the other planets – look like spinning tops. Contrary Uranus rolls around its orbit like a bowling ball on an alley with its equator nearly straight up and polar axis sticking out the sides.

To account for the crazy tilt, astronomers postulate a collision with a large, planet-sized body soon after the formation of Uranus from the dusty, rocky debris orbiting the sun called the protoplanetary disk. One problem with this scenario is that the disk should have only contained smaller objects that were in the process of accreting or gathering together under the influence of gravity to form the planets we know and love.

Uranus and some of its 27 moons photographed by the Hubble Space Telescope. They revolve counterclockwise as seen from the planet's north pole. Credit: NASA/ESA

In a new study, Alessandro Morbidelli, of the Observatoire de la Cote d’Azur in Nice, France, used computer simulations to find that two smaller collisions would have done the job nicely.

“The standard planet formation theory assumes that Uranus, Neptune and the cores of Jupiter and Saturn formed by accreting only small objects in the protoplanetary disk,” said Morbidelli. “They should have suffered no giant collisions.”

If only one big smack happened, it turns out that Uranus’ moons would be orbiting the planet backwards (clockwise seen from the north) instead of how we see them today. But if two smaller collisions were involved, the moons end up going the right way. This jives with the idea that only smaller bodies populated the protoplanetary disk.

To climb your way to Uranus, look about three outstretched fists to the upper right of Jupiter to spot Gamma in the Great Square. Jupiter, Gamma and Alpha form straight line. From there, use binoculars to navigate from Gamma to the star Omega in Pisces and then use the more detailed map below to complete your journey to Uranus. Created with Stellarium

Uranus is currently in the constellation Pisces the Fish and well-placed for viewing from 9 p.m. on. At magnitude 5.7, Uranus is faintly visible with the naked eye from a dark rural location, but we’ll spare ourselves the squinting and use binoculars to make it easy. If you’ve never seen the planet orbits the sun in the same amount of time as a typical human lifetime – 84 years – maybe it’s time for a visit. I wish I could say Uranus is right next to a bright star and easy to look up, but it’s not. Don’t fret, we’ll get you there.

In this closeup map, start with Omega, which is to the left of a small asterism of stars called the "Circlet". If you place Omega at the top of your view, Uranus will be the brightest "star" near the bottom. It's next to a slightly fainter star I've marked. Created with Chris Marriott's SkyMap software

Face east and find brilliant Jupiter, then shoot a line up to Gamma Pegasi, the lower left corner star in the Great Square of Pegasus. Now grab your binoculars and look a little more than one binocular field of view (about 5 degrees) to the lower right of Gamma to find Omega. Omega is 4th magnitude and visible from suburban and rural skies with the naked eye. With Omega in view, look toward the bottom of your binocular field and you’ll see two stars – the brighter one on top is the planet Uranus, the fainter is a star.

That star is handy, because you can use it to gauge the planet’s slow movement to the west in the coming months. If you own a telescope, the planet mimics what the Earth must also look like from afar – a tantalizing blue disk. Magnifications of 75x and up will easily show it. Bon voyage! I hope you enjoy your visit to the 7th planet.

How to spend 3 years on Mars without really trying


Think you might enjoy a 3-year ride aboard the Mars rover Opportunity? Don’t worry, you won’t need to pack food or sleeping bag. The entire 13-mile trek from Victoria Crater to the rim of Endeavour Crater happens over 3 minutes and 309 still images. This video, released by NASA today, is series of separate images snapped at the end of each drive. You’ll feel like Lawrence of Arabia as you travel across endless sand dunes, barren stretches of cracked rocky ground and several crater “oases”.  Hit the full screen button and hit the trail. Don’t forget to watch for the rim of Endeavour Crater rising in the distance mid-movie on.

The moon glides by Jupiter and the Pleiades star cluster in the next few nights. Created with Stellarium

The moon will pay homage to Jupiter and the Pleiades over the next few nights as its moves eastward across the sky. Tonight watch for it above and right of the planet; tomorrow the two will rise in tandem in the east.

The moon always offers up a reason to keep an eye on the night sky whether that’s something as dramatic as a lunar eclipse or as simple as its daily orbital motion. The more you look, the more familiar you become with how the sky works.

Rayed craters make tonight’s full moon spectacular

At full moon, the sun, Earth and moon are nearly in a straight line. An observer on Earth (blue) sees sunlight illuminating the moon's face from directly behind. Illustration: Bob King

Tonight’s the Full Hunter’s Moon, so be sure to spend a bit of time polishing up your moon tan with a stroll outdoors. A full moon is always directly opposite the sun in the sky and rises around sunset.  For Duluth, Minn., moonrise is at 5:57 p.m. or 32 minutes before sunset. To find moonrise time for your location, click HERE and key in your city, state or country. Be sure to add one hour to the times shown to convert to Daylight Saving Time.

During other lunar phases, we only see a part of the moon because of the varying angles between Earth, sun and moon. At full phase, all three orbs are lined up. The sun shines over the Earth’s “shoulder” hitting the moon’s face square on and lighting up one whole side of the lunar globe. Just as a light shining directly in your face hides the shadows cast by your nose, cheekbones and yes, your wrinkles, so the sun shining in the moon’s face hides all shadow detail. The result: a flat, pasty, two-dimensional-looking moon.

Without shadows to reveal lunar contours and the craggy details of crater walls and mountain peaks, most amateur astronomers don’t bother looking at the full moon. Besides, it’s about the only time we can get some rest, right? But I’m here to tell you that I’ve been smitten the past few years by the spectacle of all the rayed craters that come into their own when the moon hits your eye like a big pizza pie.

The four biggest and easiest to see rayed craters are visible in all their glory during tonight's full moon. Credit: Frank Barrett

Rayed craters are craters surrounded by halos of impact debris that were excavated when meteorites and asteroids struck the moon long ago. Pulverized rocks from those impacts shot out like fountains miles above the moon’s surface before falling back and blanketing the vicinity of the newly-formed craters. Some of the falling rocks were large enough to create secondary impact craters which in turn exposed more fresh crustal materials. That’s why the rays are bright compared to much of the lunar surface – the impacts that made them happened relatively recently.

Recent in astronomy is always a dubious term. In the case of rayed craters, the impacts occurred in the past billion years compared to 3-4 billion for the majority of the craters we see. Over time, exposed material on the moon’s surface darkens due to a constant pounding by subatomic particles streaming from the sun called the solar wind.

The youngest and most magnificent rayed crater is Tycho located near the “bottom” or south end of the moon. It’s only 109 million years and its rays stretch across many hundreds of miles. Tycho and the trio of Copernicus, Kepler and Aristarchus comprise the best and the biggest of the rayed craters. All can be seen with the naked eye though any pair of binoculars will make the task much easier. While shadow detail may be compromised at full moon, rays shine their brightest then.

See all those tiny white spots? Through a telescope the moon offers up dozens more rayed craters. They speckle the disk like glitter - a sight to see! Photo: Bob King

If you own a telescope, I’m going to ask you to take the next step and examine the moon at low to medium magnification tonight. Yes, you’ll feel like you’re going blind in one eye but rest assured, it’ll be worth it. Splayed across the disk – especially the central area – are many dozens of additional rayed craters. There’s nothing like the sight of them. Centered on their respective, freshly-punched craters, I’m reminded of brilliant beacons, tiny explosions, stars and flares. What will you see? May your sky be clear tonight.

Did distant comets quench a thirsty Earth?

A striking active prominence issues from the big sunspot group 1305 as it approached the western limb of the sun last Thursday. Prominences are towering flames of incandescent hydrogen gas many thousands of miles long often associated with sunspot groups. Credit: John Chumack

A beautiful, bright sun shines outside my window this morning. It was preceded by the setting moon and the onset of dawn, both of which I saw while hunting for Comet Elenin. In the briefest of intervals, I watched the sky go dark around 5:45 a.m. and then the lights slowly come back up with twilight after six. Try as I might however, I couldn’t convince myself of seeing the comet through the big 15-inch scope. Maybe there was a bit of fuzz there, maybe not. I used low power, medium power and even the power of imagination but nothing I tried convinced me Elenin was there. I’ll be out again around the 23rd or 24th when conditions will be much better. Until then, happy trails Comet E!

Comet Hartley 2 photographed by the Deep Space/EPOXI spacecraft in 2010. Credit: NASA

Last week European astronomers using the Herschel Space Observatory announced they’d found water in Comet Hartley 2 with almost the same composition of water found in the Earth’s oceans. You might remember Hartley 2 which passed near Earth in October 2010 and became faintly visible with the naked eye for a time. It was also the target of a close flyby by the Deep Impact mission a month later.

The question of where our planet got all its water has been hotly debated. The Earth grew over a period of 1-200 million years 4.3-4.5 billion years from the accumulation of millions of meteorites and asteroids. Heat arising from all that impacting material and the decay of radioactive elements (which release heat energy) melted our little globe, causing the heavier metals like iron and nickel to sink to the core with lighter rocks floating to the top to form the planet’s crust. Our world was once a glowing ball of hot magma – not exactly the kind of place you’d find water sloshing about.

That’s why scientists believe the water that’s now so plentiful and makes our world so distinctive had to be ‘delivered’ later after things cooled down. Since comets are composed largely of water ice and there are billions of them – especially in the early solar system when there was so much more ‘junk’ around – they seemed the perfect choice as a delivery mechanism to quench our planet’s thirst.

A neutron (in blue) joins hydrogen's single proton to make deuterium, represented by the chemical formula 2H.

One problem: almost all comets astronomers have studied so far contain twice as much deuterium in the hydrogen that makes the H in their H2O. Deuterium? The most common form of hydrogen has only one proton in its nucleus circled by a single electron, but 1 out of 6,420 hydrogen atoms in the Earth’s oceans also has a neutron paired up with that proton. The addition of the neutron doubles the mass of the hydrogen which is why D2O (D for deuterium) is nicknamed ‘heavy water’. If comets really are responsible for bringing water to Earth, why don’t our oceans have more heavy water? Enter the European Space Agency’s Herschel Space Observatory, the largest space-based scope currently in orbit. Its 138-inch (3.5 meter) diameter mirror and optical system are optimized to study the sky in infrared light.

This illustration shows the orbit of Comet Hartley 2 in relation to those of the five innermost planets. The comet made its latest close pass of Earth in October 2010, at which time Herschel observed the comet. Water shows as a big blue bump in the comet's light spectrum (right). Credits: ESA/AOES Medialab; Herschel/HssO Consortium

Herschel studied Comet Hartley 2 and discovered that its water has almost the same composition – regular vs. heavy water – as the Earth’s oceans. Most of the comets previously studied are thought to have formed closer to Jupiter and Saturn and then booted into the outer solar system’s Kuiper Belt through gravitational interactions with those planets. Comet Hartley 2 is different. Its birthplace was the frigid Kuiper Belt, where the deuterium to hydrogen ratio may have been very different from the one in comets formed closer to the sun.

Beyond the orbit of the most distant planet Neptune lies a vast region populated by icy asteroids and comets called the Kuiper Belt. Comets like Hartley 2 are believed to have formed here 4.5 billion years ago. Later some of them migrated inwards and may have collided with Earth, delivering water to the early planet's parched surface. Credits: ESA/AOES Medialab

So the water that makes our planet the wettest, wildest place in the solar system may still have come from comets, but from ones formed in the far reaches of the solar system. Astronomers using the Herschel scope will now be looking at other comets to confirm their hypothesis.

Comet Elenin sighted in the morning sky

This photo was taken around 5:45 a.m. on Oct. 7 through a 5-inch refracting telescope. The bit of fuzz marked by the line may be Comet Elenin or electronic noise picked up during the exposure. The faintest stars shown are dimmer than 15th magnitude. Credit: Mike Holloway

Amateur astronomers have been busy the past few mornings with telescopes and cameras searching for what’s left of Comet Elenin. I’m aware of at least a half-dozen attempts to see the comet, all but one of which resulted in a negative or uncertain result. Leonid Elenin’s photograph posted in my Oct. 6 blog may possibly show a fragment of the comet.

This morning was the best opportunity to look because the comet was moderately high in the eastern sky (about 23 degrees or “two fists”) during a narrow window of darkness between moonset and twilight. Observing from a mountain location over one mile high near Leon in northern Spain, dedicated comet observer Juan Jose Gonzalez saw Elenin as a faint, diffuse haze of magnitude 10.7 with a short tail pointing northwest. The comet had no central brightening and measured 6 arc minutes across or half the distance between Mizar and its companion star Alcor in the Big Dipper. Gonzalez was using an 8-inch Schmidt-Cassegrain telescope, and seeing conditions were very good at the time.

His is the only positive observation so far. The news gave me a jolt of hope that I and others might still see it. Photographs and other attempts have either shown a tiny 18th magnitude object or a suspected faint patch of light. These earlier observations were made when the comet was lower in the sky and its light more readily absorbed by the thicker, hazier air near the horizon. Gonzalez is an expert observer working under very dark skies. He routinely sees faint comets that escape the attempts of other less experienced amateur astronomers, myself included.

Still, why the disparity between his and Leonid Elenin’s 18th magnitude estimate of the comet’s brightness? Two factors may be at play. Elenin’s was based not only on a photograph, but also when the comet was much lower in the sky. I don’t know the field of view of his photo, but if it’s small – and especially with the comet much lower – it might not show the distended, faint coma but rather a fragment inside. That fragment, if that’s what it is, is obviously very faint. Elenin is still not sure if what he photographed is the comet or just noise.

Meanwhile, Gonzalez observed the comet much higher up with a wider field of view. Although unable to see any fragments – they’re too faint to spot visually – his wider field of view, darker sky (due to higher elevation) and very perceptive eye allowed him to see the entire coma and even a short tail. Based on the details of his observation, the coma would have looked like the faintest puff of light just a little brighter than the sky background. Although 10.7 magnitude is not faint per se, that brightness is spread across 6 arc minutes of diffuse haze, making the comet appear quite dim. Having compared my observations with Gonzalez’s for a number of years now, I’m guessing it would have been very faint from my dark sky site even in my 15″ reflector. No one to my knowledge photographed the comet this morning with a wide-field telescope. Had they, we’d have a better basis for comparison.

Detailed finder map showing Comet Elenin with bright Regulus at lower right, 6th magnitude stars 34,37 and 42 Leonis and fainter stars to 12th magnitude. North is up. 'E' is the comet's position at 5:45 local time for the UK, while 'P' shows the comet's position at 5:45 a.m. for the Pacific time zone. Created with Chris Mariott's SkyMap software

Tomorrow morning (Oct. 10) offers one last opportunity to see the comet before moonlight cuts it to the quick. Since the nearly full moon will set about 15 minutes after the start of twilight, there will be no true darkness, but it may prove just dark enough for the comet to make a very brief appearance before dawn grows too bright. Take heed! Comet Elenin is dim and diffuse and will prove a challenge even for amateurs with larger telescopes and good maps. Use the map above to help you find it. The comet will be about 4 degrees northeast of Regulus.

After tomorrow, a bright moon will make it virtually impossible to see the comet until October 21, when Elenin will once again be sufficiently high in the east to tackle before moonrise. After the 21st, conditions rapidly improve – by the 24th the comet will be high in the southern sky before the start of morning twilight.

Sparks swirl from a bonfire in the backyard. Photo: Bob King

I realize that all this talk about such a dim comet may be overmuch for some of you reading this, but had Elenin not broken to pieces in August, it’s possible we’d be seeing it in binoculars by now. What’s visible now is the dim, expanding dust cloud from the vaporization of icy-dusty cometary fragments. Speaking of which, it sounds like the eastern hemisphere had a fine Draconid meteor shower last night. We were cloudy here in Duluth, Minn. For fun I built a bonfire in the backyard and watched a homemade meteor shower of orange sparks fly to the heavens.

Befriend two lonely stars during tonight’s Draconid meteor storm

A bright meteor is a sight that can leave an impression for a lifetime. The Draconid shower - also called the Giacobinids - will peak tonight. Credit: John Chumack

Tonight’s the big night. Earth passes through dusty filaments left by Comet Giacobini-Zinner more than a century ago. As we do, dust and sand-sized particles will vaporize as fiery meteors from a point in the sky in the constellation Draco the Dragon. Peak meteor activity is very brief and occurs during mid-afternoon for North America. The sky will be dark at that time over Europe, Africa and the Middle East, making that vast region perfect for watching the spectacle, which is expected to produce from 750 to 1,000 meteors per hour. When a meteor shower is that prolific, it’s more properly called a meteor ‘storm’.

If you live in the western hemisphere, check the sky anyway during late twilight and early evening in case a few should come our way. Spaceweather.com has a live meteor radar link set up where you can listen to the ‘pings’ or echoes from passing meteors via the Air Force Space Surveillance Radar in Texas. The facility transmits a 216.98 MHz signal into the sky 24 hours a day, 7 days a week. Meteors, satellites and spacecraft passing overhead reflect those signals back to Earth. Another good resource is the American Meteor Society’s Draconid website, where you’ll find visibility maps, background information and much more. Let’s hope predictions comet true.

For the very latest results on meteor counts, please click HERE. ** Update 8 p.m. CDT: The shower peaked between 8-8:30 p.m. London, England time with a maximum rate of about 400 meteors per hour.

The moon and stars Deneb Kaitos and Fomalhaut form a large triangle in the southeastern sky this evening. The map shows the sky facing southeast around 9:30-10 p.m. local time. Created with Stellarium

While you’re out watching for javelins of flaming comet dust, turn around to enjoy the sight of the waxing gibbous moon in the southeast. Because of the moon’s glare, you won’t see many stars in its vicinity, but well below it, the bright star Fomalhaut (FOE-ma-low) in the faint constellation of Pisces Austrinus the Southern Fish and the somewhat fainter Deneb Kaitos (DE-neb KYE-tos) still hold their own.

Artist view of Fomalhaut-b, the Jupiter-sized planet circling the star Fomalhaut. Credit: NASA

Deneb Kaitos, the brightest star in Cetus the Whale, is an Arabic name meaning ‘whale’s tail’. It’s an orange giant star similar to brilliant Arcturus found off the Big Dipper’s handle in the western sky.

Fomalhaut is surprisingly close to Earth – only 25 light years – and has a Jupiter-sized planet with three times that planet’s mass revolving around it with a period of 875 years. It was among the very first (and few) extrasolar planets to be directly photographed with the Hubble Space Telescope.  That was in 2004 and 2006. More recent observations have found the planet, named Fomalhaut b, in a different position than expected and too bright for its size. Either its calculated orbit is wrong or perhaps the object isn’t a planet after all. Further observations will make a determination one way or another. And that’s how science works -  cherished ideas often require refinement and sometimes even end up on the cutting room floor.