Comets Archives

March 5, 2013December 23, 2015 by Bob King

Comet PANSTARRS Crosses Paths With Zodiacal Light

The tapering wedge of the zodiacal light reaches from the western horizon on March 3, 2013 toward the bright Planet Jupiter at top. Credit: Bob King

With the much-anticipated PANSTARRS comet emerging into the evening sky this week, we might keep our eyes open to another sight happening at nearly the same time. If you live where the sky to the west is very dark, look for the zodiacal light, a tapering cone of softly-luminous light slanting up from the western horizon toward the bright planet Jupiter near twilight’s end.

It makes its first appearance about 75 minutes after sunset and lingers for an hour and a half. Sunlight reflected from countless dust particles shed by comets and to a lesser degree by colliding asteroids is responsible for this little-noticed phenomenon. Comets orbiting approximately in the plane of the solar system between Jupiter and the sun are its key contributors. Jupiter’s gravity stirs the works into a pancake-like cloud that permeates the inner solar system.

The zodiacal is formed of dust left behind by comets orbiting between Jupiter and the sun and forms a pancake-like structure in the plane of the planets. Illustration: Bob King

More of us would be more aware of the zodiacal light if we knew better when and where to look. While a dark sky is essential, you don’t have to move to the Atacama Desert. I live 9 miles from a moderate-sized, light-polluted city; the western sky is terrible but the east is plenty dark and ideal for watching the morning zodiacal light in the fall months.

Near its base, the cone easily matches the summer Milky Way in brightness and spans about two fists held horizontally at arm’s length. At first glance you’d be tempted to think it was the lingering glow of twilight until you realize it’s nearly two hours after sunset. The farther you follow up the cone, the fainter and narrower it becomes. From top to bottom the light pyramid measures nearly five fists long. In other words, it’s HUGE.

The pyramid-shaped zodiacal light cone is centered on the same path the sun and planets take across the sky called the ecliptic. This map shows the sky 90 minutes after sunset in early March facing west. Created with Stellarium — The pyramid-shaped zodiacal light cone is centered on the same path the sun and planets take across the sky called the ecliptic. This map shows the sky facing west 90 minutes after sunset in early March. Created with Stellarium

The zodiacal light is centered on the same path the sun and planets take through the sky called the ecliptic, an imaginary circle that runs through the familiar 12 constellations of the zodiac. Every spring, that path intersects the western horizon at dusk at a steep angle, tilting the light cone up into clear view. A similar situation happens in the eastern sky before dawn in October. Of course the light’s there all year long, but we don’t notice it because it’s slanted at a lower angle and blends into the hazy air near the horizon.

The zodiacal light we see at dusk is a portion of the larger zodiacal dust cloud that extends at least to Jupiter’s distance (~500 million miles) on either side of the Sun, making it the single biggest thing in the Solar System visible with the naked eye. Under exceptional skies, like those found on distant mountaintops or far from city lights, the cone tapers into the zodiacal band that completely encircles the sky.

The gegenschein is the small, oval glow within the zodiacal band seen in this photo taken at the European Southern Observatory in Chile. Credit: ESO / Yuri Beletsky

Exactly opposite the sun around local midnight, you might see an enhancement in the band called the gegenschein (GAY-gen-shine). This eerie oval glow is caused by sunlight shining directly on interplanetary dust grains and then back to your eye. A similar boost happens for the same reason at the time of full moon.

Deep connections abound throughout the universe. Over time, much of the comet dust in the zodiacal cloud either spirals inward toward the sun or gets pushed outward by solar radiation. The fact that we can still see it today means it’s continually being replenished by the silent comings and goings of comets.

Comet C/2011 L4 PANSTARRS photographed with a 200mm telephoto lens over Bridgetown, Western Australia on March 3. Credit: Jim Gifford — Comet C/2011 L4 PANSTARRS photographed with a 200mm telephoto lens over Bridgetown, Western Australia on March 3.
Credit: Jim Gifford

Consider Comet L4 PANSTARRS. Dribs and drabs of dust sputtered from this comet during its current trip to the inner solar system may find their way into the zodiacal cloud to secure its presence for future sky watchers. How wonderful then the comet and the ghostly light should happen to be at their best the very same time of year.

Zodical light touching the Seven Sisters star cluster also known as the Pleiades March 19, 2012. Credit: Bob King

Now through March 13 is the ideal time for zodiacal light viewing. If you begin your evening with Comet PANSTARRS, stick around until nightfall to spot the light. Face west and cast a wide view across the sky, sweeping your gaze from left to right and back again. Look for a big, hazy glow reaching from the horizon toward the Planet Jupiter. After the 13th, the waxing moon will wash out the subtle light cone for a time. Another “zodiacal window” opens up in late March through mid-April when the moon comes up too late to spoil the view.

As you take in the sight, consider how something as small as a dust mote, when teamed with its mates, can create a jaw-dropping comet’s tail, meet its end in the fiery finale of a meteor shower or span a billion miles of space.

February 28, 2013December 23, 2015 by Bob King

Comet PANSTARRS Cranks up the Volume

The comet photographed with a 300mm lens. Both the main dust tail and the shorter, fainter Type III dust tail are seen. Credit: Michael Mattiazzo

Brand new photos from amateur astronomers Michael Mattiazzo and Jim Gifford, both of Australia show the current view of Comet C/2011 L4 PANSTARRS down under, and gives sky watchers in the northern hemisphere hope for great views of in little more than a week. The comet has been brightening steadily and now shines around magnitude 2.6, just a little fainter than the stars of the Big Dipper. More images below:

Comet L4 PANSTARRS on February 28 through an 11-inch telescope. Credit: Michael Mattiazzo — Comet L4 PANSTARRS from Castlemaine, Victoria, Australia on February 28 through an 11-inch telescope. Click for more photos. Credit: Michael Mattiazzo

On February 28, Mattiazzo spotted the comet and a small portion of its dust tail in evening twilight 6 degrees above the western horizon. Using large binoculars he could trace the tail to 1.5 degrees or three lunar diameters. PANSTARRS also has a second fainter dust tail, called a Type III tail, composed of heavier dust particles, dimly visible in the photo below alongside the brighter Type II tail.

Comet L4 PANSTARRS low in the western sky over Western Australia Feb. 27, 2013. Details: 400mm lens — Comet L4 PANSTARRS low in the western sky over Bridgetown, Western Australia Feb. 27, 2013. Click for more photos. Details: 400mm lens, 4-second exposure at ISO 5000. Credit: Jim Gifford

A third ion tail, while not currently visible with the naked eye, shows up well in photographs. Dust tails form when the heat of the sun vaporizes dust-laden ices in the comet’s nucleus; solar photons – literally light itself – gently pushes the dust away from the comet’s head into a long, beautiful tail. Gases like carbon monoxide and cyanogen, which are normally neutral, get their energy levels pumped up by the sun’s ultraviolet light, shed their outer electrons and become “ionized.” The same UV light causes the gases to fluoresce a pale blue.

Additional info: Comet PanSTARRS: How to See it in March 2013

Comets often develop two tails as they near the sun - a curved dust tail and straight, ion tail. Credit: NASA — Comets often develop two tails as they near the sun – a curved dust tail and straight, ion tail. Dust tails reflect sunlight and appear yellowish. Ion tails glow blue when comet gases are ionized by UV light from the sun and re-emit it as blue. Credit: NASA

Dust tails generally follow the comet’s curving orbit and assume the shape of a gently-curved arc; ion tails are straight as a stick and point directly away from the sun. Once carbon monoxide molecules have been ionized, they’re susceptible to the magnetic force that flows from the sun as part of the solar wind. The wind with its entrained solar magnetism sweeps by the comet at some 300 miles per second (500 km/sec.) and blows the ion tail straight back exactly opposite the Sun.

With PANSTARRS sprouting tails right and left and peak brightness predictions still around magnitude 1 or 2, get ready for this herald of the new season.

Here’s bascially a naked-eye view of PANSTARRS, taken by Dave Curtis on February 22, 2013 from Dunedin, New Zealand. “The comet was just visible with the naked eye in the twilight,” Dave said. It was taken with a Canon 5D3 and a 70-200mm lens at 70mm:

Comet PanSTARRS on feb. 22, 2013 from Dunedin, New Zealand. Credit: Dave Curtis.

February 27, 2013December 23, 2015 by Elizabeth Howell

3 Comets That Fizzled

An artist's conception of a comet. Credit: NASA/JPL-Caltech

Take a dirty snowball in space and hurl it towards the Sun. I dare you… and then make a prediction as to how that will look.

This is the problem comet scientists face when talking about how bright a comet will appear from Earth. They’re imaging a conglomerate of dust, ice and other materials millions of miles away. After figuring out where the comet will go, then they have to predict how it will behave.

It’s a science, to be sure, but an unpredictable one. That’s why it’s so hard to figure out how Comet ISON will fare when it gets closer to the Sun in November 2013. It could blow into pieces before arriving. It could break up when it gets close to the Sun. Or, it could live up to wildest expectations and shine so brightly you’ll be able to see it in daylight.

Veteran comet-gazers can name a few visitors that didn’t perform as well as predicted. Michael Mumma, who is with the NASA Goddard Space Flight Center’s solar system exploration division, was the lead for the agency’s scientific campaign on many comets of the past few decades. In an e-mail to Universe Today, he shared what made three comets less spectacular than predictions.

Comet Kohoutek (1973)

Comet Kohoutek in 1973. Credit: NASA/University of Arizona

Billed by some as the comet of the century, Comet Kohoutek was predicted to pass close to the Sun after it was discovered in March 1973. NASA initiated “Operation Kohoutek” to keep an eye on the comet from a network of observatories in the sky, on the ground and even telescopes in mid-air.

Mumma joked that Kohoutek was a great career launcher for him, as a spectrometer that searched for ammonia ended up getting sustained funding for further development. But the comet was a visual disappointment, he acknowledged.

“The hype surrounding Comet Kohoutek was inspired by two predictions of its possible brightness, made by a recognized senior comet scientist. The NASA spokesman chose to promote the brighter of the two, that predicted the comet would become as ‘bright as the full Moon’. He usually mentioned (softly) that we couldn’t be certain it would actually brighten that much – but the press usually ignored that disclaimer,” Mumma wrote.

“Actually, the comet really did fizzle, failing to reach even the fainter estimate – probably because at discovery it was far from the Sun and activated by something other than water ice. Under those circumstances, any prediction was bound to be highly uncertain.”

Halley’s Comet (1986)

Halley's Comet in 1986. Credit: NASA — Halley’s Comet in 1986. Credit: NASA

Halley’s is the most famous periodic comet, meaning that it returns to the inner solar system over and over again. Its bright appearance made it show up repeatedly in the historical record, most famously in the Bayeux Tapestry after it arrived in 1066 shortly before William the Conquerer successfully led the Norman Conquest of England. However, astronomers in each era saw the comet’s appearance as separate, unpredictable events.

English astronomer Edmond Halley, in examining the astronomical record in 1705, supposed that a comet with similar properties that appeared every 75 years or so was probably the same comet. Ever since then, astronomers and the public alike eagerly await each appearance. The 1910 visit was particularly spectacular, making the press set high expectations for 1986. However, the comet was much further away from the Sun in the 1980s and was fainter.

According to Mumma, the comet did not actually fizzle. Many press reports just got the brightness of the comet wrong, leading the public to believe the comet was less spectacular than predicted.

“It was a bright comet, just as scientists predicted. However, it was much brighter in the southern hemisphere than in the northern, as predicted. From Christchurch (New Zealand), and again from Cairns (Australia), it was large and the brightest object in the sky – easily seen with the unaided eye.”

As a scientific sidenote, Mumma’s team probed the comet with NASA’s Kuiper Airborne Observatory and, using infrared fluorescence spectroscopy that Mumma developed, found water for the first time in a comet.

Comet Austin (1990)

A negative image of Comet Austin. Credit: European Southern Observatory

In 1989, Sky & Telescope published a cover article on Comet Austin with the eye-catching headline: “Monster Comet is Coming!” As with Halley, many people anticipated this would be a bright comet, easily visible with the naked eye. In the book Hunting and Imaging Comets, United Kingdom amateur astronomer Martin Mobberley pointed out it was a great object in telescopes or binoculars, but not so much with the eye alone.

“Austin was less bright than some had predicted, but it was bright enough to permit major scientific successes,” Mumma added in his e-mail to Universe Today. “My team detected CO (carbon monoxide) and methanol in that comet, among the first detections of these molecules in comets at infrared wavelengths.”

All in all, these comets show that it’s really hard to figure out what they look like when they get by Earth. This means that nobody knows exactly how ISON will behave until it’s almost upon us.

February 26, 2013December 23, 2015 by Nancy Atkinson

Is a Comet on a Collision Course with Mars?

Simulation of the close approach of C/2013 A1 to Mars in Celestia using info from the Minor Planet Center. Credit: Ian Musgrave/Astroblog.

There is an outside chance that a newly discovered comet might be on a collision course with Mars. Astronomers are still determining the trajectory of the comet, named C/2013 A1 (Siding Spring), but at the very least, it is going to come fairly close to the Red Planet in October of 2014. “Even if it doesn’t impact it will look pretty good from Earth, and spectacular from Mars,” wrote Australian amateur astronomer Ian Musgrave, “probably a magnitude -4 comet as seen from Mars’s surface.”

The comet was discovered in the beginning of 2013 by comet-hunter Robert McNaught at the Siding Spring Observatory in New South Wales, Australia. According to a discussion on the IceInSpace amateur astronomy forum when the discovery was initially made, astronomers at the Catalina Sky Survey in Arizona looked back over their observations to find “prerecovery” images of the comet dating back to Dec. 8, 2012. These observations placed the orbital trajectory of comet C/2013 A1 right through Mars orbit on Oct. 19, 2014.

However, now after 74 days of observations, comet specialist Leonid Elenin notes that current calculations put the closest approach of the comet at a distance of 109,200 km, or 0.00073 AU from Mars in October 2014. That close pass has many wondering if any of the Mars orbiters might be able to acquire high-resolution images of the comet as it passes by.

But as Ian O’Neill from Discovery Space points out, since the comet has only been observed for 74 days (so far), so it’s difficult for astronomers to forecast the comet’s precise location in 20 months time. “Comet C/2013 A1 may fly past at a very safe distance of 0.008 AU (650,000 miles),” Ian wrote, “but to the other extreme, its orbital pass could put Mars directly in its path. At time of Mars close approach (or impact), the comet will be barreling along at a breakneck speed of 35 miles per second (126,000 miles per hour).”

Elenin said that since C/2013 A1 is a hyperbolic comet and moves in a retrograde orbit, its velocity with respect to the planet will be very high, approximately 56 km/s. “With the current estimate of the absolute magnitude of the nucleus M2 = 10.3, which might indicate the diameter up to 50 km, the energy of impact might reach the equivalent of staggering 2×10¹º megatons!”

An impact of this magnitude would leave a crater 500 km across and 2 km deep, Elenin said.

Fragments of Shoemaker-Levy 9 on approach to Jupiter (NASA/HST)

While the massive Comet Shoemaker–Levy 9 (15 km in diameter) that crashed into Jupiter in 1994 was spectacular as seen from Earth orbit by the Hubble Space Telescope, an event like C/2013 A1 slamming into Mars would be off the charts.

Astronomers are certainly keeping an eye on this comet, and they will refine their measurements as more data comes in. You can see the orbital parameters available so far at JPL’s Solar System Dynamics website.

We’ll keep you posted.

Sources: Astroblog, IceInSpace, SpaceObs, Discovery Space

February 22, 2013April 26, 2016 by David Dickinson

Comet PANSTARRS: How to See it in March 2013

Comet 2011 L4 PanSTARRS imaged from Argentina by Luis Argerich on February 13th, 2013. (Credit: Luis Argerich - Nightscape photography. Used with Permission).

Great ready. After much anticipation, we could have the first naked eye comet of 2013 for northern hemisphere observers in early March. As discussed earlier this week on Universe Today, 2013 may well be the Year of the Comet, with two bright comets currently putting on a show in the southern hemisphere and comet C/2012 S1 ISON set to perform the closing cometary act of 2013. But while comet C/2012 F6 Lemmon won’t be visible for northern hemisphere residents until April, Comet C/2011 L4 PanSTARRS (which we’ll refer to simply as “Comet PanSTARRS” from here on out) may well become a fine early evening object in the first two weeks of March.

That is, if it performs. Comets are often like cats. Though we love posting pictures of them on the Internet, they often stubbornly refuse to perform up to our expectations. Some comets have been solid performers, like Hale-Bopp in 1997. Others are often promoted to great fanfare like Comet Kohoutek in 1973-74, only to fizzle and fade into notoriety.
Continue reading “Comet PANSTARRS: How to See it in March 2013”

February 20, 2013December 23, 2015 by Nancy Atkinson

Infographic: What’s the Difference Between a Comet, Asteroid and Meteor?

'Name That Space Rock' -- describes the difference between those flying rocks from space. Credit and copyright: Tim Lilis. Used by permission.

With all the various space rocks flying by and into Earth last Friday, perhaps you’ve been wondering about the correct terminology, since a rock from space has different names depending on what it is made of and where it is.

Infographics artist Tim Lillis has put together a primer of sorts, in the form of an infographic, describing the different between a comet, asteroid, meteoroid, meteor and meteorite.

Asteroids are generally larger chunks of rock that come from the asteroid belt located between the orbits of Mars and Jupiter. Sometimes their orbits get perturbed or altered and some asteroids end up coming closer to the Sun, and therefore closer to Earth.

Comets are much like asteroids, but might have a more ice, methane, ammonia, and other compounds that develop a fuzzy, cloud-like shell called a coma – as well as a tail — when it gets closer to the Sun. Comets are thought to originate from two different sources: Long-period comets (those which take more than 200 years to complete an orbit around the Sun) originate from the Oort Cloud. Short-period comets (those which take less than 200 years to complete an orbit around the Sun) originate from the Kuiper Belt.

Space debris smaller than an asteroid are called meteoroids. A meteoroid is a piece of interplanetary matter that is smaller than a kilometer and frequently only millimeters in size. Most meteoroids that enter the Earth’s atmosphere are so small that they vaporize completely and never reach the planet’s surface. And when they do enter Earth’s atmosphere, they gain a different name:

Meteors. Another name commonly used for a meteor is a shooting star. A meteor is the flash of light that we see in the night sky when a small chunk of interplanetary debris burns up as it passes through our atmosphere. “Meteor” refers to the flash of light caused by the debris, not the debris itself.

If any part of a meteoroid survives the fall through the atmosphere and lands on Earth, it is called a meteorite. Although the vast majority of meteorites are very small, their size can range from about a fraction of a gram (the size of a pebble) to 100 kilograms (220 lbs) or more (the size of a huge, life-destroying boulder).

Thanks again to Tim Lillis for sharing his infographic with Universe Today. For more info about Tim’s work, see his Behance page, Flickr site, Twitter, or his website.

February 19, 2013December 23, 2015 by Bob King

The Year of the Comets: Three Reasons Why 2013 Could be the Best Ever

Comet L4 Panstarrs photographed from Australia at dawn on Feb. 17, 2013 with a telephoto lens. A bright head and short tail are visible. Credit: Joseph Brimacombe

2013 could turn out to be a comet bonanza. No fewer than three of these long-tailed beauties are expected to brighten to naked eye visibility. Already Comet C/2011 L4 PANSTARRS has cracked that barrier. Sky watchers in Australia have watched it grow from a telescopic smudge to a beautiful binocular sight low above the horizon at both dusk and dawn. A few have even spotted it without optical aid in the past week. Excited reports of a bright, fan-shaped dust tail two full moon diameters long whet our appetite for what’s to come.

Recent brightness estimates indicate that the comet could be experiencing a surge or “second wind” after plateauing in brightness the past few weeks. If the current trend continues, PanSTARRS might reach 1st or 2nd magnitude or a little brighter than the stars of the Big Dipper when it first becomes visible to northern hemisphere sky watchers around March 7. That’s little more than two weeks away!

Comet Panstarrs will make its first appearance for northern hemisphere sky watchers around March 7 low in the western sky after sundown. Notice that the comet gets no higher than 10 degrees - about one fist held at arm's length - through much of the month. Illustration created using Chris Marriott's SkyMap software — Comet Panstarrs will make its first appearance for northern hemisphere sky watchers around March 7 low in the western sky after sundown. Notice that the comet gets no higher than 10 degrees – about one fist held at arm’s length – through much of the month. Illustration created using Chris Marriott’s SkyMap software

Every day between now and March 10, when PanSTARRS’ orbit takes it closest to the sun, the comet is expected to slowly increase in brightness. Later this month it disappears in the solar glare, but when it re-emerges into evening twilight around Thursday, March 7, northern and southern hemisphere observers alike will get great views. Binoculars should easily show a bright head and swept-back tail pointing away from the sun. And don’t forget to mark your calendar for March 12. On that date the thin lunar crescent will join the comet for a rare photogenic pairing. To locate and keep track of PanSTARRS, you’ll need the following materials and circumstances:

* An unobstructed view of the western horizon
* Clear, haze-free skies at dusk
* Pair of binoculars
* A map

I can’t help you with all of the above, but this map will help point you in the right direction. Once you find a location with a great western view, watch just above the horizon for a fuzzy, star-like object in your binoculars. While it’s possible the comet will be bright enough to see with the naked eye, binoculars will make finding it much easier. They’ll also reveal details of tail structure too subtle to be visible otherwise.

Incredible detail is seen in the gas tail of F6 Lemmon in this photo made with a 19.6-inch telescope Feb. 17, 2013. Credit: Martin Mobberley

Comet PanSTARRS has some cometary company. C/2012 F6 Lemmon is currently plying its way through the constellation Tucana the Toucan, shining right around the naked eye limit at magnitude 5.5. To the unaided eye, Lemmon looks like a dim fuzzy spot. Binoculars show a thin gas tail and big, bright head or coma. Comas develop around the comet’s icy nucleus as sunlight vaporizes dusty ice to create a short-lived atmosphere that in the shape of a luminous teardrop. Long-exposures like the one above reveal richly-detailed streamers of carbon monoxide and other gases fluorescing in sunlight in the comet’s fashionably skinny tail.

Lemmon is slowly receding from Earth this month, but should remain just above the naked eye limit for some time as it continues to approach the sun. Northern hemisphere observers will need to be patient to see this one. After looping around the sun on March 24, the comet will pop back into the morning sky near the familiar Square of Pegasus asterism in early May. If we’re lucky, Lemmon may still be near the naked eye limit and visible in ordinary binoculars.

Cmet C/2012 F6 (Lemmon), imaged on Feb. 19. 2013 remotely from Q62 (iTelescope Observatory, Siding Spring). Credit: Ernesto Guido and Nick Howes, Remanzacco Observatory. — Cmet C/2012 F6 (Lemmon), imaged on
Feb. 19. 2013 remotely from Q62 (iTelescope Observatory, Siding Spring). Credit: Ernesto Guido and Nick Howes, Remanzacco Observatory.

Before we move on to the comet with the greatest expectations, I want to mention Comet 2P/Encke. Encke was the only the second comet to have its orbit computed – way back in 1819 by German astronomer Johann Encke. This year it’s making its 62nd observed return to Earth’s vicinity. That’s a lot of visits, but when your orbital period is only 3.3 years – the shortest known of any comet – you can’t help but be a regular visitor. While not expected to brighten to naked eye level, the comet will be a fine sight in modest-sized telescopes glowing around 8th magnitude when it tracks between the Big Dipper and Leo the Lion this October.

Comet ISON in the western sky shortly after sunset in late November this year. Illustration created with Chris Marriott's SkyMap software — Comet ISON in the western sky shortly after sunset in late November this year. Illustration created with Chris Marriott’s SkyMap software

Our final comet, Comet C/2012 S1 ISON, was discovered last September by Russian amateurs Vitali Nevski and Artyom Novichonok while making observations for the International Scientific Optical Network (ISON). At the time, it was farther than Jupiter and impossibly faint, but once ISON’s orbit was determined, astronomers realized the comet would pass only 1.1 million miles from center of the sun (680,000 miles above its surface) on November 28, 2013.

Comet ISON belongs to a special category of comets called sungrazers. As the comet performs a hairpin turn around the sun on that date, its ices will vaporize furiously in the intense solar heat. Assuming it defies death by evaporation, ISON is expected to become a brilliant object perhaps 10 times brighter than Venus. Or brighter. Some predict it could put the full moon to shame. If so, that would occur for a brief time around at perihelion (closest approach to the sun) when the comet would only be visible in the daytime sky very close to the sun. When safely viewed, ISON might look like a brilliant, fuzzy star in a blue sky.

A color image of comet Ison taken on February 5, 2013 from northern Arizona. Credit: Chris Schur.

Most of us won’t risk burning our retinas staring so close to sun. Instead we’ll watch with anticipation as the comet sprouts a long tail while ascending from the western horizon just after sunset in late November and early December. Whatever it does, sky watchers in both southern and northern hemispheres will ringside seats when ISON’s at its best.

Right now the comet’s whiling away its time in the constellation Gemini the Twin and still very faint. Come September, it should be easily visible in small telescopes in the morning sky. The first naked eye sightings could happen in late October. Many of us hope the comet will be one for the record books, a worthy successor to C/2006 P1 McNaught, the last “great comet” to dazzle human eyes. It reached peak magnificence for southern hemisphere sky watchers in January 2007.

C/2006 P1 McNaught became a memorable sight for observers living in southern latitudes in January 2007. Will Comet ISON do the same? Credit: Wikipedia

Three bright comets – and one modestly bright – might be enough for a year, but there could be surprises. Dozens of new comets are discovered each year by professional sky surveys and amateur astronomers. Most are faint and move along their appointed paths unnoticed by 99.9% of the world’s population, but every so often a new one comes along that blossoms into a spectacle. How many of those are out there tonight waiting to be discovered?

February 6, 2013December 23, 2015 by Ken Kremer

Deep Impact Images Spectacular incoming Comet ISON – Curiosity & NASA Armada Will Try

Image Caption: This image of comet ISON (C/2012 S1) ) from NASA’s Deep Impact spacecraft clearly shows the coma and nucleus on Jan. 17/18, 2013 beyond the orbit of Jupiter. See the dramatic new movie sequence below. It combines all 146 80-second clear filter exposures for a total integration time of 11680 seconds (about 3.25 hours). Individual frames were shifted to align the comet at the center before coadding. By keeping the comet centered and adding all of the images together, the stars effectively get smeared so the long streaks are the trails of background stars. Some have called it the “Comet of the Century.” Credit: NASA

NASA’s legendary Deep Impact comet smashing spacecraft has just scored another major coup – Imaging the newly discovered Comet ISON. The comet could possibly become one of the brightest comets ever late this year as it passes through the inner Solar System and swings around the Sun for the very first time in history – loaded with pristine, volatile material just raring to burst violently forth from the eerie surface, and is therefore extremely interesting to scientists. See the Movie below

“Comet ISON was just imaged by Deep Impact out by Jupiter on Jan. 17 and 18,” said Dr. Jim Green, Director of NASA Planetary Sciences at NASA HQ, in an exclusive interview with Universe Today on the campus of Princeton University. “We will try to look at ISON with the Curiosity rover as it flies past Mars, and with other NASA assets in space [along the way]. It should be spectacular!”

“We are all, ops team and science team, thrilled that we were able to make these observations when the comet was still more than 5 AU from the sun,” said Deep Impact Principal Investigator Prof. Michael A’Hearn of the University of Maryland, in an exclusive interview with Universe Today.

ISON could potentially become the next “Great Comet”, according to NASA. Deep Impact is the first spacecraft to observe ISON.

“We are continuing to observe ISON – it is observable from Deep Impact into mid-March 2013,” A’Hearn told me.

ISON will be the 4th comet observed by Deep Impact. On July 4, 2005 the spacecraft conducted a close flyby of Comet Tempel 1 and delivered a comet smashing impactor that made headlines worldwide. Next, it flew near Hartley 2 in Nov. 2010. In January 2012, the spacecraft performed a long distance imaging campaign on comet C/2009 P1 (Garradd). And it has enough fuel remaining for an Asteroid encounter slated for 2020 !

“NASA’s assets at Mars should be able to observe ISON because it will fly really, really close to Mars!” Green said with a big smile – and me too, as he showed me a sneak preview of the brand new Deep Impact movie.

“ISON observations are in the cue for Curiosity from Mars surface and from orbit with NASA’s Mars Reconnaissance Orbiter (MRO) – and we’ll see how it works out. It should be pretty spectacular. We will absolutely try with Curiosity’s high resolution Mastcam 100 camera.”

“LRO (NASA’s Lunar Reconnaissance Orbiter) also has a good shot at ISON.”

“Because of the possibility of observations of for example ISON, with probes like Deep Impact is why we want to keep NASA’s [older] assets viable.”

146 visible light images snapped by Deep Impact just days ago on Jan. 17 and 18, have been compiled into a dramatic video showing ISON speeding through interplanetary space back dropped by distant star fields – see above and below. The new images were taken by the probes Medium-Resolution Imager (MRI) over a 36-hour period from a distance of 493 million miles (793 million kilometers).

“A composite image, combining all of the Jan 17/18 data – after cleaning up the cosmic rays and improving the S/N (signal to noise ratio) clearly shows the comet has a coma and tail,” said Tony Farnham, a Deep Impact research scientist at the University of Maryland, to Universe Today.

Video Caption: This series of images of comet C/2012 S1 (ISON) was taken by the Medium-Resolution Imager (MRI) of NASA’s Deep Impact spacecraft over a 36-hour period on Jan. 17 and 18, 2013. At the time, the spacecraft was 493 million miles (793 million kilometers) from the comet. Credit: NASA/JPL-Caltech/UMD

ISON is a conglomeration of ice and dust and a long period, sun-grazing comet.

“It is coming in from the Solar System’s Oort cloud at the edge of the Solar System”, said Green, and was likely disturbed out of its established orbit by a passing star or other gravitational effects stemming from the Milky Way galaxy. “It will pass within 2.2 solar radii during perihelion and the Sun will either blast it apart or it will survive.”

Despite still being in the outer Solar System and a long distance from the Sun, ISON is already quite “variable” said A’Hearn, and it’s actively spewing material and ‘outgassing”.

The tail extending from the nucleus was already more than 40,000 miles (64,400 kilometers) long on Jan. 18. It’s a science mystery as to why and the Deep Impact team aims to try and determine why.

In addition to imaging, Deep Impact will also begin collecting long range spectral observations in the next week or so to help answer key questions.

“In mid-February, the solar elongation will allow IR (infrared) spectra for a few weeks,” A’Hearn elaborated.

“The 6-7% variability that we observed in the first day of observing shows that there is variable ‘outgassing’, presumably modulated by rotation of the nucleus. We hope to pin down the rotational period with the continuing images.”

“The interesting question is what drives the outgassing!”

Since ISON is still a very great distance away at more than 5 AU, data collection will not be an easy task. The comet is 5.1 AU from the Sun and 5.3 AU from Deep Impact. And the mission could also be imperiled by looming slashes to NASA’s budget if the Federal sequester actually happens in March.

“Getting spectra will be a real challenge because, at these large heliocentric and geocentric distances, the comet is really faint. However, maybe we can test whether CO2 is driving the outgassing,” Ahearn explained.

“Since we have the only facility capable of measuring CO2, it will be important to observe again in our second window in July-August, but that depends on NASA finding a little more money for us.”

“We, both the ops team and the science team, are funded only for the observations through March,” A’Hearn stated.

Although observing predictions for the brightness of comets are sometimes notoriously wrong and they can fade away precipitously, there is some well founded hope that ISON could put on a spectacular sky show for observers in both the northern and southern hemispheres.

The comet will continue to expand in size and grow in brightness as it journeys inward.

“ISON might be pretty spectacular,” said Green. “If things work out it might become bright enough to see during the day and be brighter than the Moon. The tail might be 90 degrees.”

Image caption: This is the orbital trajectory of comet C/2012 S1 (ISON). The comet is currently located just inside the orbit of Jupiter. In November 2013, ISON will pass less than 1.1 million miles (1.8 million kilometers) from the sun’s surface. The fierce heating it experiences during this close approach to the sun could turn the comet into a bright naked-eye object. Credit: NASA/JPL-Caltech

The best times to observe the comets head and growing tail will be from Nov. 2013 to Jan. 2014, if it survives its closest approach to the Sun, known as perihelion, on Nov. 28, 2013 and doesn’t break apart.

There’s no need to worry about doomsday predictions from conspiracy theorists. At its closest approach next Christmas season on Dec. 26, 2013, ISON will pass by Earth at a safe distance of some 40 million miles.

A pair of Russian astronomers only recently discovered the comet on Sept. 21, 2012, using the International Scientific Optical Network’s 16-inch (40-centimeter) telescope near Kislovodsk.

The study of comets has very important implications for understanding the evolution of not just the Solar System but also the origin of life on Earth. Comets delivered a significant portion of the early Earth’s water as well as a range of both simple and complex organic molecules – the building blocks of life.

Ken Kremer

Image caption. Deep Impact images Comet Tempel 1 alive with light after colliding with the impactor spacecraft on July 4, 2005. CREDIT: NASA/JPL-Caltech/UMD

January 10, 2013December 23, 2015 by Fraser Cain

Three Views of Comet C/2012 K5 (LINEAR)

While we’re all waiting with bated breath to see what Comet ISON decides to do in 2013, the Solar System is continuing to throw ice balls our way. The latest one keeping astronomers busy is Comet C/2012 K5 (LINEAR), which has been visible in the sky for the last couple of weeks, and should keep us entertained for a few more.

In late December, the comet was a fairly compact iceball, but it flared up nicely in early January, producing a sizable tail, well worth searching for with a set of binoculars or small telescope.

A trio of astrophotographers pooled their efforts on January 4/5 and created this series of time lapses showing the comet from their different equipment setups, and different locations. First up, Mark Behrendt from Chicago, IL used an 8″ Celestron and captured the images using a Canon T3i DSLR camera. Then Cory Schmitz used his 10″ Zhumell Dobsonian telescope, captured images on a Canon T2i from Ames, IA. Finally, Mike Rector in Plattsburg, NY used a Celestron Omni XLT 150, with a Canon 350D camera.

The three time lapses were stitched together by Cory Schmitz into the composite video you’re seeing attached to this article.

Although he wasn’t able to capture a time lapse, Mike Phillips in Apex, NC was able to capture a single long exposure image of the comet using his 14″ homebuilt Newtonian “Akule”.

Comet C/2012 K% (LINEAR) captured by Mike Phillips

Here’s an article from Astrobob giving more details on the comet, and its predicted path over the rest of this month. Bob shares a few more images of the comet taken by astronomers from around the world.

As Bob says, C/2012 K5 is a nice little warmup comet. Nothing dazzling, but a worthwhile challenge to test your astrophotography skills and knowledge of the sky. But in 2013, the sky show is going to get better and better. C/2011 L4 PANSTARRS will arrive in March and provide a much brighter comet in the night sky. And if we’re lucky, ISON will blaze at the end of the year, giving us one of the brightest comets in years.

Want to see more of their work? Mark, Cory and both Mikes are regular participants in our Virtual Star Party, where we connect several telescopes up live into a Google+ Hangout and show what’s happening in the night sky.

January 10, 2013December 23, 2015 by Nancy Atkinson

New Comet Discovered During ‘Stargazing Live’ Event

A new comet discovered on January 8, 2013 named Comet P/2013 A2 (SCOTTI) was found remotely from the Haleakala-Faulkes Telescope. Credit: Nick Howes, Ernesto Guido and Peter Phelps.

This week is the BBC’s Stargazing Live, and there have been all sorts of events in the UK for what has become a national stargazing celebration. Excitingly, during one event where astronomers were coordinating imaging with students in UK schools, a new comet was discovered.

“To say we’re over the moon would be an understatement,” said Nick Howes, who is the Faulkes Telescope Pro-Am programme manager. He along with his colleague at the Remanzacco Observatory in Italy, Ernesto Guido helped facilitate the discovery. “This was one of the trickiest comets we’ve ever worked on, faint at magnitude 20, with a minuscule tail. It took all our efforts for several hours to confirm it with the 2 meter scopes. It’s fantastic that with the third episode of Stargazing Live coming up and focusing on comets, that we managed to nail this one during the airing of the live show.”

This is the third year of Stargazing Live, which brings together astronomical societies, museums and discovery centers for local events as well as live broadcasts on the BBC.

Howes and Guido decided on trying to image this target, as analysis of the Minor Planet Centre’s NEOCP target list showed that one of the newly detected but as yet unclassified objects was likely to be a comet.

“We’d selected this target based on the preliminary data published by the minor planet center,” Howes said, “but then the power of social networking helped out even more.”

With only one set of limited observations on it by the Spacewatch Observatory, Howes communicated via the social network site Twitter with Jim Scotti, an astronomer in Arizona, who first observed this object.

“It became clear from speaking to Jim, that they thought they had something, but in following with IAU rules would not say what,” Howes said. “But he encouraged us to perform additional observations to make sure what we had was indeed what we suspected from the orbit…a new comet!”

The new object at magnitude 20, billions of times fainter than the human eye can see was then imaged by Howes and Guido using Faulkes Telescope North.

Fortunately, the elevation of the comet in the sky also permitted them to request additional observations from Peter Phelps at Hazlemere school in the UK. “The data from Faulkes North was not 100% clear, as the object was so faint, but we suspected it was a comet, and asked for more images,” Howes said.

The extra images, from Faulkes South showed the comet very near to a bright field star, but were enough to convince Howes and Guido that it was indeed a comet.

The minor planet center later on the 8th January confirmed this and cited the Faulkes observations in the discovery circular and telegrams:

The new Comet is called P2012 A2 Scotti CBET is 3376 Cbet nr. 3376, issued on 2013, January 08, announces the discovery of a new comet (discovery magnitude 19.5) by J. Scotti with the 691 Steward Observatory, Kitt Peak, on images obtained with the 0.9-m f/3 reflector + CCD on January 06.2. The new comet has been designated P/2013 A2 (SCOTTI).

The team have been observing and imaging comets and asteroids all week with UK schools, and on Wednesday January 9th had a full day devoted to detecting and refining orbits on Kuiper belt objects in the far reaches of the solar system with a large number of schools. This is part of an ongoing research collaboration with the Lowell Observatory in Arizona.

Congrats to all involved!

Sources: Nick Howes, Remanazacco Observatory