Comet C/2012 K5 sprouts tails of wonder to brighten the night

Seen up close by spacecraft, comets resemble asteroids, only they’re made of ice, dust and rock. When near the sun, solar energy causes comet ices to vaporize and form a coma and tail. Comet Tempel 1 is about 4 miles across; Hartley 2, 1.4 miles. Most comets are no bigger than about 15 miles in diameter. Credit: NASA

Comets are changeable by nature. When far from the sun, they’re frozen, inert bodies that look like points of light in large telescopes. No warm, fuzzy outside, no tail.  But once a comet’s orbit takes it “downtown” to the inner solar system, heat from the sun vaporizes dust-laced ices to form a hazy atmosphere around the comet called a coma. Comas can grow up to 60,000 miles or more across or nearly as big as Jupiter. While impressive in size and appearance, they’re extremely rarified and possess little mass.

How a tail develops and grows as a comet approaches and then recedes from the sun along its orbit. Ion tails always point directly away from the sun. Credit: NASA

Being made of nearly nothing, makes it easy for the sun to fashion them into tails by the sun. Radiation pressure – literally the pressure of sunlight – pushes back dust inside the coma to form a yellow-hued dust tail.

Ultraviolet light from the sun ionizes or electrifies atoms and molecules inside the comet’s temporary atmosphere. One of the most common gases found in comets is carbon monoxide. Yep, the same stuff that comes out of your car’s tailpipe. As the sun’s magnetic field washes across the solar system like so many waves rippling a pond, it sweeps ionized carbon monoxide molecules out of the coma to form a second, blue-colored ion tail.

Ion tails always point directly away from the sun much like a wind vane, while dust tails tend to follow the curve of the comet’s orbit. Depending on where the comet is in relation to Earth, tails can appear long and narrow, short and spiky, fan-like or even hide for a time behind the coma.

The changing faces of comet C/2012 K5 from mid-Dec. 2012 through Jan. 6, 2013. The tail originally pointed northwest, then flopped over to the northeast. On the 24th, notice the ion tail (blue) and fainter yellow dust tail. The yellow dust tail displayed a nice curve a few nights ago but is now straightening out. Credit top row (l-r): Michael Jaeger, Gerald Rhemann, Jaeger. Bottom: Jaeger, Rolando Ligustri and Ligustri.

Current bright telescopic comet C/2012 K5 has displayed both types of tails during its travels across the evening sky the past week. Because the comet plunged from directly above the plane of the planets to below it around the time of its closest approach to Earth (Dec 31, 2012), our perspective on it has been changing daily.

The appearance of C/2012 K5’s tail has varied as the comet passed through the plane of the solar system as seen from the moving Earth. Arrows show direction of movements. Credit: JPL/NASA

I’ve seen comets’ tails morph this way and that, but few as quickly as C/2012 K5’s twists and turns. You’ve seen a few pictures of the comet in this blog already, but today I thought I’d put them all together to give you a perspective on the changeable nature of this icy wonder.

Comet C/2012 K5 shown every 2 nights around 8 p.m. CST. The comet slows down in the coming weeks as it distance from Earth continues to increase. Stars shown to mag. 8. Right-click, save and print to use at the telescope. Created with Chris Marriott’s SkyMap software

Sadly, the comet is fading but it remains visible in 7×50 or 10×50 binoculars from a dark sky; through an 8-inch or larger telescope, the coma – along with it bright central nucleus – opens up into beautiful, broad dust tail fanning to the northeast. I’ve included an updated chart to help you find it.

Tomorrow I’ll have some news on another comet, C/2012 S1 ISON, which is expected to put on a spectacular show later this fall.

Bundle up for tonight’s Quadrantid meteor shower; K5 comet update

The Quadrantid radiant, or point in the sky from the meteor shower originates is found below the handle of the Big Dipper. I’ve shown the sky looking northeast around 2 a.m. Later that morning, the radiant will be high in the northern sky. Created with Stellarium

Yes Bobby, there is life after the Geminids. Last month’s meteor shower was arguably the best of 2012, but more are on the way. We start the year with a shower that originates from one of astronomy’s extinct constellation, Quadrans Muralis.

Although defunct, the group of dim stars was around long enough in the late 1700s to lend its name to the Quadrantid meteor shower.

The Quadrantids are reliable but forever a tease. Unlike most showers, which typically toss meteors our way up to several days before and after maximum, the Quads’ activity is limited to a span of 6 hours centered on the peak. That peak can bring a blast of up to 100 meteors per hour, but after that, the show’s pretty much over.

Quadrantid meteor on Jan. 4, 2011. Details: ISO 400, 30-second exposure and 8mm fisheye lens. Credit: John Chumack

This year’s maximum occurs at 13:00 Greenwich time or 7 a.m. CST tomorrow morning Jan. 3 for the Midwest. That’s well into morning twilight for the eastern half of the U.S. but still close enough to peak to make the shower worth watching.

Observers living in the western U.S. and across Hawaii and east Asia are favored because their skies will be dark for a longer time centered around the expected time of maximum.

No matter where you are, light from the waning gibbous moon will compromise meteor counts.

To watch the Quadrantids, set your alarm for tomorrow morning between 2 and 6 a.m. and face east or north away from the bright moon. Your eyes will adapt better to the darkness in those directions, letting you see more (and fainter) meteors. For mainland U.S. observers, the closer to dawn you’re out the better. I plan on rising about 5 should the sky clear.

Peter Jenniskens, senior research scientist at NASA’s SETI Institute, traces the Quads origin to the asteroid 2003EH1, a likely extinct comet. So yes, tomorrow morning we’ll be watching the remains of an extinct comet radiate from an extinct constellation. What could be more apropos?

Comet C/2012 K5 Monday evening Dec. 31, 2012 from Austria. Compare its appearance to the photo taken below in mid-December. The comet’s tail points northeast. Credit: Michael Jaeger

Did someone say comets? Rarely have I seen a comet’s appearance change so rapidly. C/2012 K5, the comet we visited in a blog three days ago, went from compact and bright to big and foggy in just a week. On Christmas morning, C/2012 K5 sported a small, bright head and a striking tail pointing northwest. Two nights ago I was in for a shock when I observed it again. The head had swelled into a big, hazy bulb with a bright, star-like center followed by a wide, much fainter, tube-like tail angled northeast.

There are at least two reasons for these radical changes – the comet was closer by a few million miles – 27 million on Monday night vs. 30 million on the 25th – and our viewing perspective is changing rapidly as C/2012 K5 dives through the plane of the solar system on about Jan. 6.

C/2012 K5 on Dec. 16, 2012 shows a small head and well-defined bright tail pointing northwest. Credit: Michael Jaeger

The comet follows a steeply inclined orbit, looping high above and plunging deep below the plane of the planets and sun. During the first half of December  skywatchers looked up above the Earth and solar system plane to see it. As C/2012 K5 plunges southward, we’re now seeing the comet more from the side.

Since a comet’s tail always points away from the sun, these changing perspectives – a combination of both the comet’s and Earth’s orbital motions – will continue to alter the tail’s direction and appearance in the coming weeks.

C/2012 K5 orbit is steeply inclined to the plane of the solar system, which is why it’s been visible in the far northern sky of late. Now the comet’s rapidly moving southward as it plunges through the plane. Credit: NASA/JPL

Despite the changes, C/2012 K5 remains bright enough to see easily in 8×40 binoculars from a dark sky. It’s a speedy beast too, leaping along at the rate of about 4 degrees per day or 1/3 the moon’s diameter per hour. When the bright core or nucleus happened to pass near a star Monday night, I could see it move in just 15 seconds at 64x in my scope.

Comets and meteor showers keep an amateur astronomer’s life interesting.

C/2012 K5 – an evening comet worth chasing

Comet C/2012 K5 photographed this morning Dec. 16, 2012 from Austria. Two tails are visible – the obvious one and a faint dust fan to the upper left of the comet’s head. Credit: Michael Jaeger

Sure I love the moon. Last night’s walk with the dog wouldn’t have been nearly as romantic without it. But tonight the moon won’t rise for an hour after twilight ends. That means the return of dark skies and the Milky Way. It’s also a perfect time to follow what has now become 2012’s brightest comet – C/2012 K5 LINEAR. Just in time it would seem!

This picture of Comet C/2012 K5 on Christmas Eve morning was made with an 8″ telescope and nicely shows the comet’s two tails. Credit: Gerald Rhemann

On Christmas morning I saw it in plain old 8×40 binoculars as a fuzzy glow near Big Dipper’s Bowl. Through a 15-inch telescope the comet was sheer beauty with a compact bright head and tail nearly as long as the full moon is wide (1/2 degree).

Currently shining around magnitude 8.5 and moving swiftly as it makes its closest approach to Earth tomorrow, C/2012 K5 is now out during convenient evening viewing hours.

The comet moves swiftly through Auriga and n. Taurus in the coming nights. Watch especially on Jan. 3 when it passes next to the bright star cluster M36. Stars shown to mag. 7.3 and map dates are for 7 p.m. CST.  Right-click, save and print a copy for use at the telescope. Created with Chris Marriott’s SkyMap software

You’ll find it still around 8-8.5 magnitude during the coming week as it skims through the bright constellation Auriga not far from Jupiter.  I have to be honest – while visible in binoculars from a reasonably dark sky, it’s no great shakes, just a patchy glow. Through a small telescope however, you’ll see the little head and at least a hint of the tail stretching off to the west.

Consider the comet a warm-up for the brighter fare coming this March when C/2011 L4 PANSTARRS makes its appearance in the evening sky. You can read more about that one  and another bright comet in my best sky events of 2013 blog.

C/2012 K5 orbit is steeply inclined to the plane of the solar system, which is why it’s been visible in the far northern sky of late. Now the comet’s rapidly moving southward as it plunges through the plane. Credit: NASA/JPL

C/2012 K5 LINEAR was discovered earlier this year by the automated Lincoln Near-Earth Asteroid Research (LINEAR) project. The joint effort by the Air Force, NASA and MIT’s Lincoln Laboratory uses a 1-meter (39-inch) telescope to discover and track Earth-approaching asteroids. In addition to thousands of new asteroid finds, the survey has picked up a few comets along the way. K5 was discovered on images taken May 25, 2012.

Facing east around 7 p.m. local time Dec. 30. Use this wide view map to locate Auriga and then the more detailed view above to find the comet. Created with Stellarium

The comet comes closest to Earth on Dec. 31 at a distance of 27.3 million miles. Now at its brightest, the comet will soon fade after about the middle of January. Stop by for a look the next clear night.