How to find and follow asteroid 2012 DA14 during Friday’s flyby

Get ready for Friday’s flyby of the 150-long rocky asteroid 2012 DA14. Credit: NASA/JPL-Caltech

Near-Earth asteroid 2012 DA14 has become a sizzling topic online and on the TV news. Not a week goes by lately when I don’t hear about “the asteroid that’s going to fly by Earth”. Yesterday John, my mailman, asked me about it.

“Supposed to be half as long as a football field,” he offered. John was right. It’s a good-sized rock – the largest we know of to approach Earth this closely.

It’s fun that folks are excited about this 150-foot long solar system vagabond. I only wish we’d all have a chance to see it. Using the charts and tips below, it’s my hope that many of you will.

2012 DA14 was discovered by astronomers in the La Sagra Sky Survey program in Spain in February 2012. With an orbital period (time it takes to go around the sun) of about 368 days it makes annual spins by Earth. Friday’s flyby will be the closest the asteroid has been for many years and the closest it will come for at least the next 30.

And we do mean close. On Feb. 15 at about 1:24 p.m. (CST), 2012 DA14 will zoom 17,200 miles above the Earth’s surface traveling at 17,400 mph. While this is a record approach for a known object of this size, other smaller asteroids have skimmed nearer yet.

We only have to look back to June 27, 2011 when 2011 MD, about 20-50 feet wide, passed just 7,500 miles overhead. No harm came to Earth’s nail-biting residents then and none will during Friday’s pass. The record by the way for the closest-known shave goes to the petite, 3-foot-long 2011 CQ1 at 3,400 miles on Feb. 4, 2011.

2012 DA14 will briefly fly between the geostationary belt of communications satellites (white dots) and the Earth during closest approach Friday Feb. 15. Notice how it comes from under the Earth, moving from south to north. Credit: Simone Corbellini

On average, we’d expect an object of 2012 DA 14′s size to get this close to the Earth about once every 40 years. An actual collision by something this big is far rarer – about once every 1200 years.

On its inbound leg, 2012 DA14 will buzz between the constellation of GPS satellites, which orbit at about 12,600 miles, and the ring of geostationary satellites located about 22,200 miles above Earth’s equator. None will be in danger because the asteroid will come up from below and pass through the empty zone between the two.

Some 300 active weather and communications satellites are parked in orbit in the ring and relay communications around the globe. When your favorite TV weatherperson flashes pictures of storms and hurricanes taken from space, you can bet it was photographed and transmitted back to Earth by a geostationary satellite. There are presently about 32 GPS satellites used by government and consumers alike to pinpoint precise locations on the ground.

Simulation of the original constellation of 24 GPS satellites orbiting Earth. Credit: Wikipedia

As the asteroid zips by, Earth’s gravity will bend its orbit, changing its orbital period from 368 to 317 days and making close approaches like this one less likely. As for 2012 DA14 striking any satellite at all, Donald Yeomans, head of NASA’s Near Earth Object Program Office at the Jet Propulsion Laboratory, says it’s “extremely remote.” Given the huge volume of space the asteroid must pass through as it swings by Earth and the tiny number of potential targets, we might liken it to a gnat in a mansion.

Despite its proximity, 2012 DA14′s tiny size means not even the largest telescopes will show it as more than a star-like point of light. If you live in eastern Europe, Asia or Australia, you’ll see the asteroid at its closest, when it not only be brightest but moving fastest. I’ve seen a few Earth-approaching asteroids, and they really can book across the sky, but few travel as fast as this one will. In just three hours centered on closest approach, 2012 DA14 will zip from the Southern Cross all the way to the Bowl of the Big Dipper!

World map with time zones. The area inside the red circle shows very approximately where the asteroid will be visible in a dark sky when it’s closest and brightest. Map credit: Wikipedia

It reaches peak brightness around 1:24 p.m. (CST) or 7:30 p.m. in London, England. While the sky will be dark there at that time, the asteroid will still not have risen in the east. We have to go travel farther east and south to catch it at its brightest. Let’s pick Athens, Greece. There the the sky will be dark early enough to spot the asteroid at its brightest (magnitude 7.4) low in Virgo around 10 p.m. local time using standard 40-50mm binoculars. Observers should look for a dim “star” slowly moving from south to north in the field of view.

A map from Heavens Above showing the entire sky from Jakarta, Indonesia. The labeled arc is the asteroid’s path during the night. Credit: Chris Peat

As we continue moving east across the globe, 2012 DA14 gets higher and higher in a dark sky. If you sense the eastern hemisphere has the best seats in the house, you’re right.

Residents of Jakarta, Indonesia for example will see the whole show from beginning to end. Fortunate sky watchers there can spot 2012 DA14 with a telescope around 1 a.m. Saturday morning Feb. 16 (local time) near the Southern Cross.

By 3 a.m. they can switch over to binoculars to catch it at maximum brightness.  At dawn, the asteroid will have made a complete south-to-north beeline from Cross to Dipper and once again require a telescope to see. What a way to spend a night out, eh?

Did I say it was moving quickly? When nearest Earth, 2012 DA14 will hurry along at 1 degree or two full moon diameters per minute. Not only will you need binoculars, you’ll also need to know exactly where to look. By the time the sky is dark across the U.S., South America and Canada Friday night, the asteroid will have slowed considerably and faded to around magnitude 11.5 -12.

Sadly, U.S. sky watchers will need a 6-inch or larger telescope to find and follow it. The good news is that the asteroid will be conveniently placed in the northern sky near the Little Dipper.

The asteroid is shown at three times for an observer in Athens, Greece Friday evening facing east around 9:45 p.m. local time. 1 = 9:45 p.m., 2 = 10 p.m. and 3 = 10:15 p.m. Stars are plotted to about magnitude 7.5, the asteroid’s brightness at the time. Credit: Chris Marriott’s SkyMap software

I’ve given much thought on how to prepare charts for viewing 2012 DA14. When brightest, it’s not only crossing a great deal of sky in a hurry, but it’s so close to Earth that viewers in say, Vienna, will see it in a somewhat different part of the sky than those in Greece. You can’t make a one-size-fits-all chart for this bugger.

What I did instead was to create two charts – one for Athens, Greece and another for the central U.S. The Greek chart shows the asteroid when closest and brightest; the U.S. chart is centered on Duluth but is useful for a larger region, because the asteroid will be far enough away at that time for the path shift to be much smaller.

Just remember that you’ll need a telescope and good knowledge of the sky to find and follow our friend from the U.S. Use the charts to locate where the asteroid will be at a particular time and then wait for it to arrive as you gaze through the eyepiece.

2012DA14 will have faded to 11.5-12.0 magnitude when it gets dark enough to see it in the U.S., so you’ll need this more detailed chart to find it. Times are Central Standard for Friday Feb. 15, 2013. North is up and stars plotted to mag. 13. Brighter stars labeled with magnitudes. Right-click, save and print out for use at the telescope. Credit: Created with Emil Bonnano’s MegaStar atlas.

I highly recommend two websites that will show you a map of 2012 DA14′s path in your local sky as well as two other options for creating your own map:

Heavens Above - Webmaster Chris Peat has prepared a special 2012 DA14 page on this well-known satellite prediction site. Head over, log in with your location and then click the 2012 DA14 link at the top of the page for a map with times. If you select a spot on the asteroid’s path and click again, you’ll be shown a detailed map with stars to 8th magnitude European, Asian and Down Under sky watchers will find these maps most useful.

* Visual SAT-Flare Tracker 3D - Select your location and click on the 2012 DA14 asteroid header. Then click on the “Best opportunity to see the asteroid from your location” link to see a star map and asteroid path. Be aware that the faintest stars shown here are only about 6th magnitude (naked eye limit), but they’ll still be quite useful for tracking; webmaster Simone Corbellini uses the very accurate JPL Horizons data (see below) for path-making.

* Do-it-yourself – If you have your own star-charting program that allows you to add new asteroids to the database, go to the Minor Planet Center and grab 2012 DA14′s orbital elements. Enter these into your program and print your own star chart. Again, because of how close the asteroid will be, its path might be somewhat different than what your program will show, but at least you’ll be in the neighborhood.

* Tedious but foolproof method – Head over to the JPL Horizon site, type 2012 DA14 into the search box, select your city, time interval (whether you want an asteroid position every 15 minutes, hour or whatever) and then click “Generate ephemeris”. You can hand-plot the positions listed onto a star chart you’ve made with your software program. Be aware that all the times are Universal Time or Greenwich Mean Time (GMT). Subtract 5 hours for Eastern time, 6 for Central and so on. This method has worked very well for me during previous close flybys.

Good luck and I hope a few of you get to see this running rock!

Mid-February bright comet update: Panstarrs, Lemmon, Bressi, Ison

Comet Panstarrs on Feb. 8, 2013 photographed with a 300mm telephoto lens from Castlemaine, Victoria, Australia. Observers describe very bright head and broad tail. Click to see more comet photos. Credit: Michael Mattiazzo.

There are a lot of icy mudballs , ie. comets, flying around up there at the moment, so let’s take a look at what’s happening. We’ll start with C/2011 L4 PANSTARRS, better known as Comet Panstarrs. It’s been slowly brightening to within naked eye range, hovering now right on the edge of visibility under dark skies. Recent observations by amateur comet observers put the comet a smidge above the naked eye limit at magnitude 5.5-5.7. It’s a snap to see in binoculars in morning twilight in the southern hemisphere. As you can tell from the photo, it has an intensely bright, almost star-like head and wide, dusty tail that’s about 1/2 degree long. It should be a most excellent sight in binoculars for both northern and southern hemisphere sky watchers when it emerges at dusk in the western sky next month. We’re only four weeks away!

What a comet! This is Comet Lemmon shot through a 5-inch widefield telescope on Feb. 8, 2013 from Possum Observatory Complex in Gisborne, New Zealand. Click for large version. Credit: John Drummond

Meanwhile, another comet has temporarily stolen the show. C/2012 F6 Lemmon has swelled into a huge, green leek of a thing, Like Panstarrs, it too is faintly visible with the naked eye (mag. 5.8) under dark skies for southern hemisphere skywatchers. How come they get all the fun?

A long, thin exclamation point of a tail shoots from Lemmon’s giant, whipped-up coma or cometary atmosphere. Good news is, the comet is still brightening and may reach 3rd magnitude, making it an easy sight even from the suburbs.

We northerners will have to be patient if we want a glimpse of this comet. Not until early May, when it swings around the sun and enters the morning sky at about magnitude 5, will we get our chance.

You can see the fading of Comet Bressi in this sequence of photos made by Rob Kaufman of Bright, Victoria, Australia.

Then there’s C/2012 T5 Bressi, a modest, unassuming comet that experienced a bright outburst in late January. In a matter of days it became 10 times brighter than expected. On Feb. 4, Bressi glowed at 9.2 magnitude and then slid to 10.5 the very next day.

Sad to say, this is a bad omen for a comet and usually means the beginning of the end. They are crumbly things after all and subject to breakup as their ices volatilize under the relentless sun. Unfortunately, the nail might get hammered into Bressi’s coffin on Feb. 24, when it reaches perihelion or closest distance from the sun (28 million miles). Some comet observers predict it will disintegrate around that time.

Reversed (negaitve) image of Comet ISON on Feb. 3. At the time, the comet was 4 times Earth’s distance from the sun. Credit: Rolando Ligustri / CARA Project

Finally we come to this year’s best hope for a brilliant comet – C/2012 S1 ISON. It’s still slowly cruising through northern Gemini and beautifully placed for telescopic observation every clear night for observers in the northern hemisphere. Would that it were a tad brighter. You still need a 12-inch or larger telescope to see this 15th magnitude fuzzy blotch. I shouldn’t be so offhanded. Ison has developed a short tail of late, lending it enough character to whet our appetite for things to come.

By late fall, ISON should be an easy binocular object in the morning sky. Come Christmas it’s likely to be a glorious sight at dusk. Tag along with me and I’ll let you know how it goes as the clocks ticks cometward.

In darkness the moon is reborn

If we could see the moon today, it would be a very thin crescent only a few degrees from the sun. Tomorrow it’s in new moon phase. Maps created with Stellarium

What’s old today but instantly becomes young again tomorrow? If you guessed the moon, you’re right! Today the moon winds up its current cycle of phases as an exceedingly thin crescent so close to the sun it’s invisible in the solar glare.

The moon’s cycle has always been a metaphor for life. Every month it’s born again as a thin crescent in the western evening sky, grows to a half-pie seven days later and reaches its full power and radiance when full at 14 days. After full, the moon’s radiance declines as its phase wanes to last quarter (21 days) and then to a whiskery crescent at dawn. Before it finally disappears in the sun’s glare, the moon, now 28 days old, reaches the end of its “life” cycle. But only briefly. The very next day, moments after new moon phase, it’s reborn again as an evening crescent.

When we run into troubles in our lives, we might look to the ever-renewing moon for inspiration.

The sky looking west-southwest a half hour after sunset Monday evening Feb. 11, 2013. You might be able to spot dimmer Mars in binoculars.

Tomorrow morning at 2:20 a.m. (CST) the moon will be exactly lined up with the sun and pass through new moon phase. Skywatchers in the western hemisphere won’t see the moon either day because it’s in the same direction as the sun and swamped by glare.

By Monday Feb. 11 however, the moon’s orbital motion will remove it far enough from the sun to be visible during evening twilight.  And there’s a bonus. The crescent will float a few degrees above the planet Mercury.

I’ve removed the atmosphere in this illustration so you can see where the moon is today at noon (CST), tomorrow morning when it reaches new moon phase and tomorrow Feb. 10 at noon. It passes north of the sun, which is in the constellation Capricornus. Notice all the planets in the neighborhood.

If we were to follow the moon today through new moon and into tomorrow, we’d notice it passes well north of the sun. Most of the time, the new moon is either north or south of the sun because its orbit is tipped about 5 degrees relative to Earth’s orbit.

The moon’s tilted orbit causes it to swing north or south (pictured here) of the sun from Earth’s perspective. A couple times a year however it crosses directly in front and a total solar eclipse is visible from somewhere on Earth. Illustration: Bob King

Over the course of its monthly cycle, it bobs up and then down along its tilted orbit. But 2 or 3 times a year, when the moon intersects the plane of Earth’s orbit at the same time as new moon phase, it crosses directly in front of the sun and we see a total solar eclipse. In fact, this is the only time we can see a new moon with the naked eye. It looks exactly like what you’d expect – a blank, black disk scrubbed free of its past life, waiting to begin the next as a tender crescent.

The new moon – black disk – is plainly visible silhouetting the sun during a total solar eclipse. Credit: Luc Viatour

Space station and (maybe) auroras return to evening sky

A gorgeous northern lights fills the sky over Faskrudsfjordur, Iceland earlier today Feb. 8, 2013. This image was taken by photographer Jónína Óskarsdóttir. Click the photo to see her eye-watering aurora photo gallery.

Alaskans, Norwegians and Icelanders have something in common this week beside the cold. They’ve all been watching displays of the northern lights which have bloomed over Arctic latitudes night after night since late January. I know they’d be happy to share the sight with us in the lower 48, and maybe they’ll have the chance.

Auroras might reach down into the northern U.S. sometime tonight through Sunday. There is a 35% chance for a major storm in far northern latitudes and a 10% chance for minor storming in the mid-north latitudes where much of the world lives. I interpret that to mean a glowing arc pierced by a few rays low in the northern sky.

While not exactly a big blast, it’s worth keeping an eye out for that greeny glow . Since the sun’s been very quiet lately, a solar flare is not behind the uptick in activity. Rather an enhancement in the solar wind is behind the current forecast.

Photo taken Feb. 1, 2013 from Quyta Lake, Northwest Territories, Canada. Looks like it was ideal time for snow-angel-making under the aurora borealis. Credit and copyright: Yuichi Takasaka – www.blue-moon.ca

Joining the night scene will be the International Space Station. It returns to the evening sky for much of the U.S. and Canada starting tomorrow and continuing the next few weeks. Take note of the fine Valentine’s Day pass. The times below are for the Duluth, Minn. region. For times and directions to look for your town, type your zip code into Spaceweather’s Satellite Flybys page or log in to Heavens Above. You can also get free e-mail alerts via NASA’s Spot the Station.

* Sat. Feb. 9 starting at 7:20 p.m. Brief pass low in the southwestern sky
* Sun. Feb. 10 at  6:30 p.m. Travels across the southern sky below Orion
* Mon. Feb. 11 at 7:15 p.m. Brilliant pass up from the west into the southern sky. Disappears into Earth’s shadow below the planet Jupiter at 7:18 p.m.
* Tues. Feb. 12 at 6:24 p.m. Cuts across bottom of Orion’s Belt about 6:28 p.m.
* Weds. Feb. 13 at 7:10 p.m.  Brilliant pass! Just when the ISS is nearly overhead, it fades away as it enters Earth’s shadow about 7:13 p.m.
* Thurs. Valentine’s Day at 6:19 p.m. Bright pass high in the southern sky. Slides under the planet Jupiter about 6:22 p.m. Time it right, and you can give your sweetheart this celestial surprise gift during your night out on the town.

Mercury and Mars twist it up at dusk

Mars and Mercury have a quick tete-a-tete tonight Feb. 7 and Friday Feb. 8 low in the western sky in the direction of sunset. The scene shows the sky about 1/2 after sunset at which time Mercury will be about 8 degrees high. That’s just shy of one fist held at arm’s length against the sky. Created with Stellarium

It’s a long shot for some, but if you’ve got a wide open western horizon and clear sky tonight (Feb. 7) and tomorrow, you can watch a very close conjunction of Mercury and Mars. Mercury is just beginning its trek into the evening twilight, so it’s still low and soaked in solar glare. That will change next week when the planet climbs farther from the sun and becomes considerably easier to see.

Mars has been hanging around in twilight for months. Being on the faint side, it’s been a binoculars-only planet for many weeks. Mercury shines two magnitudes brighter at -1 and should just be visible with the naked eye in the darkening sky. Just the same, I’d bring binoculars if I were you. Scan a little ways above the west-southwest horizon about 30 minutes after sundown to locate Mercury. Once you see it, you’ll spot Mars about 3/4 degree (1.5 moon diameters) to its upper left tonight and 1/2 degree to its lower left Friday evening.

Good luck!

Move over Orion, it’s the Big Dog’s turn

The sky facing south around 9-9:30 p.m. local time in mid-February. Canis Major lies to the right and below the constellation Orion and represents a large dog. Created with Stellarium

Orion the Hunter claims the southern sky as his own during evening hours in early February, but the times are changing. Nipping at his heels is the Dog Star Sirius and the rest of the stars that comprise the constellation Canis Major the Greater Dog. ‘Greater’ because there’s also a ‘lesser’ dog in the neighborhood called Canis Minor.

Truthfully, this constellation’s so small, it looks more like a dog bone treat for the bigger Canis.

Open your door and look outside at 8 o’clock and you can’t miss Orion’s three belt stars. If you shoot a line downward through the belt toward the southern horizon, you’ll soon arrive at scintillating Sirius, flashing like a silent firecracker in the turbulent air common at lower elevations.

Dangling below Sirius are some half dozen stars in the shape of a musical triangle. These form the legs, tail and head of Canis Major. Connect the dots the next clear night and you’ll see they do form the likeness of a dog jumping at your feet.

Mythological depiction of Canis Major and nearby Lepus the Hare. That rabbit better watch out. Credit: Urania’s Mirror atlas

Canis Major has been described in myth as Orion’s hunting companion and also as Laelops, “a dog so swift that no prey could outrun it”, according to Ian Ridpath, author of Star Tales. The Big Dog doesn’t have to look far for a snack -  just beneath Orion, Lepus the Hare munches contentedly in the stellar garden.

It wasn’t too many weeks ago that you had to stay up late to catch the canine constellation, but now I see it’s nudging Orion from its top spot by 9:30 p.m. As the Earth spins, stars appear to rise in the east, reach their greatest height when due south and set in the west. By month’s end, Canis Major will be due south around 8 p.m. and Orion will have taken a hike to the west.

The Greater Dog constellation topped by Sirius, nicknamed the “Dog Star” for obvious reasons. The star cluster M41, located just a short distance below Sirius, is a very pretty sight in binoculars and very easy to find. Photo: Bob King

If the nightly east-west drift of stars is due to Earth’s rotation, what causes the seasonal drift of the stars? Why doesn’t Orion always stay in the same place week after week, month after month? Blame it on Copernicus. He made the claim, outrageous for his time, that the Earth moved around the sun. Throughout antiquity and into the Middle Ages people thought that if the Earth moved, every time you jumped off the ground, the planet would rush away and leave you behind. Since that didn’t happen, it was obvious the Earth must stand still.

Few understood that EVERYTHING – the Earth, the jumper, birds and atmosphere – were all moving at the same speed and so appeared to be at rest relative to each other. The same thing happens when you’re flying at 550 mph in a plane. Once the plane has reached a constant speed, you’re hardly aware you’re moving. And since you, your laptop and that ginger ale are all traveling at 550 mph, they don’t go flying around the plane. This habit of things to stay put as long as they’re all moving at the same speed is called inertia.

Because our planet orbits the sun, we see into different directions in space over the weeks and months of a year. In January (right), Orion dominates the southern sky; in April it’s Leo and in June, Scorpius. The whole cycle repeats every year. Illustration: Bob King

OK, back to the Big Dog. As the Earth orbits the sun, our perspective on the nighttime sky changes over the weeks and months. At 10 p.m. in mid-January Orion stands straight up in the southern sky, but at 10 p.m in February, he’s been replaced by Canis Major. Come 10 p.m. in April, Leo the Lion will be high in the south and Orion will have set in the west.

As the weeks and months go by, we peer into a different direction of sky just as a runner sees different groups of fans as she runs the 1500-meter on a race track. Like many good things in skywatching, the cycle repeats anew every year.

Tadpole comet swims under Deep Impact’s gaze

Video of Comet C/2012 S1 ISON compiled from images taken by NASA’s Deep Impact spacecraft on Jan. 17-18, 2013.

Comet ISON looks like a tadpole in the video, but we all know that tiny tadpoles grow into big green frogs. So will the comet when it brightens to naked eye visibility later this year. Well, not a frog exactly. A great comet is more like a colossal tadpole with a long, bright tail that can stretch many degrees across the sky.

NASA’s Deep Impact probe, the one that gave us amazing closeup pictures of comets Tempel 1 and Hartley 2, is back in the business of comet watching. NASA directed the spacecraft to track and image Comet ISON as part of a campaign to learn all we can about this frozen ball of ice and dust during its first trip to the inner solar system.

Comet ISON photographed on Jan. 20, 2013 using the Vatican Observatory’s 72-inch telescope. A short tail, fuzzy coma (comet atmosphere) and bright nucleus are visible. Inside the nucleus is the comet body itself, believed to be about 2 miles across. We can’t see it directly because it’s shrouded by its own gas and dust. Click photo to learn more. Credit: Carl Hergenrother

Like Comet C/2011 L4 PANSTARRS, ISON is believed to come from the Oort Cloud, a gigantic, spherical reservoir of comets in the distant outer solar system that reaches a third of the way to the nearest star system, Alpha Centauri. As the sun travels around the center of the Milky Way galaxy, gravitational nudges from neighboring stars can give an Oort Cloud comet a little push and send it falling toward the inner solar system.

The ensuing sun-bound voyage is THE definition of a slow boat to China. It takes millions of years for a comet like ISON to inch toward the inner sanctum, but when these first-timers finally get a taste of the sun’s heat, pristine, dust-laden ices are quick to vaporize.

Artist depiction of Oort Cloud, sphere filled with millions of inactive comets extending some 9 trillion miles from the sun. In 1932 and again in 1950 astronomers Ernst Opik and Jan Hendrik Oort postulated the existence of the cloud to explain where comets with long orbital periods originate.

When the photos were taken, ISON was 493 million miles from the spacecraft or about as far as Jupiter is from the sun. Despite this vast distance, we can already see a haze of gases called the coma from vaporizing ice and a short tail more than 40,000 miles long pointing southeast. Amateur astronomers have recorded a similar appearance with telescopes and cameras here on Earth.

Comet ISON is a hot topic whether you’re a professional astronomer, amateur or brand new to skywatching because it belongs to a special group of comets called sungrazers. As the name implies, these comets passed exceptionally close to the sun before swinging back out into the depths of space. ISON will arc only 130,000 miles from the sun or a little more than half the Earth-moon distance on November 28, 2013. Assuming the comet doesn’t break to pieces under the intense heat and gravitational stress, we should see a long-tailed spectacle with the naked eye both before and after closest approach.

Comet McNaught (C/2006 P1) was our most recent “Great Comet”. As the photo attests, it was a spectacular sight in mid-January 2007 for skywatchers in the southern hemisphere. Some predict Comet ISON has what it takes to become the next great comet. Credit: NASA

Although I don’t have the details on the comet’s size, many astronomers believe ISON is big enough to survive intact and make for a great show this fall and winter in both northern and southern hemispheres.

Have no fear about any effects on Earth except for jaws dropping in wonder (assuming predictions hold true); Comet ISON will only come as close as 40 million miles on Dec. 26, 2013.

New nova erupts in Cepheus

The new nova in Cepheus is just below the W of Cassiopeia near the attractive open star cluster NGC 7510. To find Cassiopeia, look halfway up in the north-northwestern sky around 7 p.m. local time. Created with Stellarium

No, I’m not talking about that Chevy Nova you muscled around town years ago. This one’s a tiny star of a thing in the constellation Cepheus the King not far from the W of Cassiopeia. Japanese amateur astronomers Koichi Nishiyama and Fujio Kabashima discovered the “new” star on Feb. 2 shining where no star had been noticed before. They reported their observation and the object was soon given the unwieldy working name of PNV J23080471+6046521.

PNV stands for ‘possible nova’ and the numbers are its celestial coordinates, akin to latitude and longitude. A day later the discovery was confirmed and the new star received the nifty official name Nova Cephei 2013 – our first of the new year.

Want to see the nova in your scope? Click and go to the AAVSO page where you can print a larger version. Just copy and paste the name PNV J23080471+6046521 into the star name box there. Credit: AAVSO

Before you get too excited, this nova is not visible with the naked eye, but a 6-inch telescope will show it. The Japanese astronomers found it shining around magnitude 10.3, plenty bright for a a small telescope, but the star has faded to around 11.7 in the past few days.No worries. Even if you’re not equipped with the right instrument and the burning desire to freeze finger tips in the cold, you can still enjoy what novas are all about.

About half a dozen novae (NO-vee) are found each year along the star rich byways of the Milky Way. These days they’re usually picked up during deliberate photographic patrols of the night sky by amateur astronomers.

Though a nova can happen anywhere in the sky, they’re more likely to be found along the band of Milky Way because that’s where the majority of stars are. Amateurs hunt there to you increase their odds of finding one.

Now that I’ve been blabbing on about the topic for four paragraphs it’s probably time to tell you a nova is NOT a new star despite it hopeful name. It’s an old star really, a very old star, but one that gets an occasional, if explosive, face lift. While we’ve been eating breakfast, lunch and dinner all our lives, a tiny white dwarf star in Cepheus has been dining on the gas of a close companion star for centuries.

A white dwarf with the mass of the sun is about the same size as Earth. Its surface temperatures is about 180,000 degrees (16x hotter than the sun). Unlike the sun, a white dwarf shines by residual heat. Nuclear fusion in its core has ended. Credit: Prof. Richard Pogge

Picture the sun with all its mass compressed to the size of the Earth and you’ve got a white dwarf. Gravity is some100,000 times stronger there than on our “fluffy” planet, so that a teaspoon of matter scooped from a dwarf’s surface weighs 5 tons.

When a white dwarf happens to be in a very close orbit about a normal star, it siphons gas from that star into a swirling accretion disk like cotton candy wound around a paper cone. From there, the material spirals down to the dwarf itself.

Hydrogen gas – the primary ingredient of most stars – gradually builds up on the dwarf’s blazing surface and becomes heated and compressed by gravity until it’s hot enough to burn or fuse. Normally nuclear fusion happens inside of stars; the energy released gradually works its way to the surface and becomes sunshine. On a white dwarf’s surface fusion happens all at once everywhere, created a powerful burst of light and energy as now-incandescent hydrogen is blasted into space. That’s a nova.

Novae happen only in very close binary star systems where a white dwarf pulls matter off its companion. The material spirals down to the dwarf’s surface and eventually ignites. Credit: NASA

We look up and see a star that was otherwise much too faint to notice suddenly become bright enough to spot in a 3-inch telescope. Some novae are brighter or closer and flare to naked eye brightness.

Novae usually flare brightest earliest and then gradually fade back down, but sometimes additional bursts are seen, so it’s fun to keep an eye on them for changes.

The out-of-the-way open cluster NGC 7510 in Cepheus isn’t far from the nova. The cluster’s about 2,400 light years away. Credit: Jim Misti

For amateur astronomers who plan to seek Nova Cephei, you’re in for a treat. Not half a degree away is the rich, box-shaped star cluster NGC 7510. I stumbled on it two nights ago when I got my first look at the nova. It’s worth a look if you’re in the neighborhood.

First drilling photos from Mars

Closeup of one of the holes drilled taken by the MAHLI (Mars Hand Lens Imager) camera taken on Feb. 3, 2013.  Grey powdery dust – could it be clay-related – lines the hole. Credit: NASA/JPL-Caltech/Malin Space Science Systems

The first pictures of the Curiosity rover’s drill in operation appeared in the raw image archive this weekend and show a gray powder piled up around the holes. Much red dust covers the Red Planet, but once you get below the surface, the true rock color is revealed.

Curiosity is test drilling at the John Klein site in Yellowknife Bay inside Gale Crater. Once it’s cleaned its sample containment container mounted above the drill with grit from the drilling process, actual sampling and analysis will begin. That’s probably still a few days away.

In this quick animation, pre-drilling and drilling photos show pebbles shifting position due to vibration from the drill. Credit: NASA

Look closely at test drill animation above and you’ll see small pebbles about a foot away shift position as the slabby rock they’re on shakes with each percussive jab of the drill. Almost like being there.

Picture of the robotic arm with the drill in position taken by Curiosity’s Mastcam on Feb. 1, 2013. Click for hi-res image. Credit: NASA/JPL-Caltech

Bizarre green meteorite NWA 7325 may be from Mercury

Wow, that’s what I call green! Green, glassy fusion crust coats one side of Ralew’s new meteorite. This is the largest of the 35 fragments, weighing just over 100g. Cube at right is 1 cm across. Click for larger version. Credit: Stefan Ralew

In April 2012 Stefan Ralew, a meteorite collector from Berlin, found himself staring at a spread of 35 green meteorite fragments for sale by a dealer in Morocco

“It was offered as a Martian (meteorite) but for me it was simply far too green,” said Ralew. Moroccan meteorite always keep an eye out for green rocks in the belief that they’re of Martian origin. Sometimes however they turn out to be nothing more than Earth rocks. Since this one was expensive, Ralew would have normally declined, but he noticed that the pieces had fusion crust, that frothy, typically dark coating of melted rock that forms when a meteorite is heated during its fall through the atmosphere.

Stefan Ralew Credit: Mirko Graul

“It was a big risk because of the high price,” said Ralew, but he sealed the deal and mailed off a piece to Dr. Tony Irving at the University of Washington, well-known for his expertise in meteorites from other planets.

After chemical analysis, Irving discovered that Ralew’s green rock was a completely new type of achrondrite (ay-KON-drite), a class of igneous meteorite that forms deep within the crust of larger asteroids and planet-sized bodies. In fact, Ralew’s green meteorite shared similarities with the planet Mercury, making it a one-of-a-kind.

Many of the more familiar achondrites that scientists and meteorite hunters have picked up here on Earth were blasted from the surface of Vesta by meteorite and asteroid impacts. Still others have been liberated from the moon and Mars. They drift through space until swept up by the ceaseless Earth. Scientists have done the math and arrived at the conclusion that meteorites from Mercury impacts should also by lying around in the deserts of the world, preserved by arid air and lack of rain. But no one had definitely identified a rock from Mercury until the green meteorite entered the scene.

A closeup of a polished, cut face of NWA 7325 shows striking green crystals of chromium diopside (a silicate mineral with chromium) and gray crystals of plagioclase, a rock also common in Earth’s crust. Click for larger version. There are a total of 345 grams (about 12 ounces) mostly in small fragments. Credit: Stephan Ralew

Other classes of achondrites called aubrites and angrites were once believed to have originated on the innermost planet, but further research points to their home on a yet-unknown asteroid or planet.

Mercury photographed by MESSENGER. The planet’s crust lacks iron and is pockmarked by countless craters. One of these impacts possibly sent NWA 7325 our way. Credit: NASA

Stefan’s meteorite, now classified as NWA 7325 (NWA=Northwest Africa, its find location), is a near-match for rocks examined from orbit by Mercury MESSENGER space probe. NWA 7325 is rich in magnesium, calcium and a silicate material laced with chromium that lends it an emerald sparkle, but it lacks iron. And that’s the key. Surface rocks on Mercury are likewise igneous and depleted in iron.

The match isn’t perfect. NWA 7325 has more calcium than it should and lacks the silicate mineral enstatite (common on Mercury), but that doesn’t worry scientists too much. Because the rock was excavated from deeper down in the crust, it would be expected to have its own unique qualities.

Mars meteorites show evidence of shock from impact in their crystal structures, and the same would be expected for rocks delivered to us from Mercury. Plagioclase, a very common mineral in Earth’s crust, and found in abundance in NWA 7325, has been completely melted, likely due to shock from the impact that sent it flying from the planet long ago.

Bubbly fusion crust on another fragment of Stefan’s meteorite. Click for larger version. Credit: Stefan Ralew

While the evidence points to a Mercury origin, we won’t really know for certain whether Ralew’s rock originated from the innermost planet until further studies are done. Scientists are still working to determinewhen those gorgeous green crystals formed as well as how long the rock coasted through space before arriving on Earth.

“Ultimately, only a sample return from Mercury may provide an answer,” wrote Irving in his group’s recent report on NWA 7325. In the meantime, Stefan’s meteorite stands as one of the most singular finds to date. It couldn’t have happened to a better guy. Ralew has a been a great friend of meteorite collectors and the scientific community for years. You can check out his website HERE.