Comet-ISON

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All ISON the Sun

Over the next month, Comet ISON will either provide skywatchers on Earth with astronomical beauty or enormous disappointment.

Thanksgiving weekend finds the visitor from Oort swinging behind the sun at more than 300,000 miles per hour (or “haulin’ ass” in scientific terms), coming only 730,000 miles from our hot ball of gas at its closest approach. To put that in perspective, Mercury orbits an average of nearly 36 million miles from the sun. Needless to say, not the friendliest place for a ball of ice and rock to be, eh?

To make things even more exciting, the sun has unleashed a coronal mass ejection (seen in the lower animation). Shouldn’t affect the comet much, though. the sun’s immense energy will put enough strain on it as it is.

Whether or not it will survive the close shave is unknown, but astronomers are watching closely (as you can see, it’s entered into view of NASA’s solar observing telescopes!). If ISON does make it through intact (perhaps lightly broiled?) December promises some superb comet watching.

For updates: Check out a live feed of its position and speed at CometISON 2013. I also recommend Phil Plait’s Bad Astronomy blog and here’s a host of links from NBC’s Alan Boyle.

In Memoriam

Comet C/2012 S1 (ISON)

Born 4.5 Billion BC, Fragmented Nov 28, 2013 (age 4.5-billion yrs old)

Born in a dusty and turbulent environment, comet ISON spent its early years being jostled and struck by siblings both large and small. Surviving a particularly violent first few million years, ISON retreated to the Oort Cloud, where it maintained a largely reclusive existence for nearly four billion years. But around 3-million B.C., a chance encounter with a passing star coerced ISON into undertaking a pioneering career as a Sungrazer. On September 21, 2012, ISON made itself known to us, and allowed us to catalog the most extraordinary part of its spectacular vocational calling.

Never one to follow convention, ISON lived a dynamic and unpredictable life, alternating between periods of quiet reflection and violent outburst. However, its toughened exterior belied a complex and delicate inner working that only now we are just beginning to understand. In late 2013, Comet ISON demonstrated not only its true beauty but a surprising turn of speed as it reached its career defining moment in the inner solar system. Tragically, on November 28, 2013, ISON’s tenacious ambition outweighed its ability, and our shining green candle in the solar wind began to burn out.

Survived by approximately several trillion siblings, Comet ISON leaves behind an unprecedented legacy for astronomers, and the eternal gratitude of an enthralled global audience. In ISON’s memory, donations are encouraged to your local astronomy club, observatory or charity that supports STEM and science outreach programs for children.

Credit: Karl Battams

Not strictly true - this’ll only happen if the comet survives its close encounter with the Sun with enough volatiles intact to make a nice tail by the time it’s close to Earth, which isn’t guaranteed.

If it does survive, though, this is going to be the comet of the century, outshining the full moon at night and possibly visible during the day.

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The latest observations from professional and amateur astronomers around the world show that the comet ISON is still very much alive, and new data suggests that it may very well survive its close swing by the Sun on November 28.

This is good news, since if it survives, the comet ISON would blossom into a naked-eye comet, sporting a long, beautiful tail across the sky. Comets are notoriously unpredictable and can surprise even experts, so for now it’s anyone’s guess what ISON will do. We’ll just have to wait and see.

Click images for authors/credit.

Possible ‘Comet of the Century’ Blazes Up in New Photos

A comet that could become one of the brightest ever seen when it flys by the sun this November is already remarkably bright and active, a new set of photos shows.

Comet ISON sports a well-defined tail of dust and gas even though it remains far from the sun, the new images from Hawaii’s Gemini North Observatory reveal. But it’s still too early to tell if ISON will live up to the “comet of the century” hype, researchers stress.

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Comet Ison ‘May Have Survived’ Brush With Sun

Astronomers tracking what they hoped would be the “comet of the century” say some of it may have survived its close encounter with the Sun.

It was first reported that the Comet Ison’s nucleus and tail had been destroyed by the Sun’s radiation and tidal forces but the European Space Agency (ESA) said the “story continues”.

The latest pictures appear to show a brightening of a chunk of the comet which has caused a surge in excitement among skygazers.

It is hard to know what has happened but experts say dust and gas are being released and the tail may be growing back.

If it is visible in the night sky, it is too soon to know how bright it will be or how long it will last.

Comet Ison, which had been hurtling through space at speeds of 845,000mph, was due to pass within 730,000 miles of the surface of the star last night.

It was expected to be met with temperatures of about 2,700C (4,892F) and an intense gravitational pull as it prepared for its solar slingshot.

Full Article

Credit: SOHO/NASA

Observers around the world are reporting a sharp increase in the brightness of sun diving Comet ISON. Formerly dim, it is now on the threshold of naked-eye visibility. Comet ISON is plunging toward the sun for a perilous pass through the solar atmosphere on Thanksgiving Day (Nov. 28th). This could be the first of many brightening events as intensifying solar heat erodes material away from the comet’s nucleus. 

Apparently, Comet ISON has surged in brightness by approximately 2 magnitudes in little more than 24 hours. If the trend continues, it could be a faint but easy naked-eye object by the end of the week.

The sudden uptick in brightness could be caused by a fresh vein of ice opening up in the comet’s nucleus. Rapid vaporization of ice by solar heat is a sure-fire way to boost a comet’s visibility. But, as NASA’s Comet ISON Observing Campaign states, “we [really] have no idea.” The comet’s nucleus is hidden from view by a hazy green atmosphere, so events in the interior remain a mystery.

http://spaceweather.com/

A new view of Comet ISON

This new image of Comet C/2012 S1 (ISON) was taken with the TRAPPIST national telescope at ESO’s La Silla Observatory on the morning of Friday 15 November 2013. Comet ISON was first spotted in our skies in September 2012, and will make its closest approach to the Sun in late November 2013.

TRAPPIST has been monitoring comet ISON since mid-October, using broad-band filters like those used in this image. It has also been using special narrow-band filters which isolate the emission of various gases, allowing astronomers to count how many molecules of each type are released by the comet.

Comet ISON was fairly quiet until 1 November 2013, when a first outburst doubled the amount of gas emitted by the comet. On 13 November, just before this image was taken, a second giant outburst shook the comet, increasing its activity by a factor of ten. It is now bright enough to be seen with a good pair of binoculars from a dark site, in the morning skies towards the East. Over the past couple of nights, the comet has stabilised at its new level of activity.

These outbursts were caused by the intense heat of the Sun reaching ice in the tiny nucleus of the comet as it zooms toward the Sun, causing the ice to sublimate and throwing large amounts of dust and gas into space. By the time ISON makes its closest approach to the Sun on 28 November (at only 1.2 million kilometres from its surface — just a little less than the diameter of the Sun!), the heat will cause even more ice to sublimate. However, it could also break the whole nucleus down into small fragments, which would completely evaporate by the time the comet moves away from the Sun’s intense heat. If ISON survives its passage near the Sun, it could then become spectacularly bright in the morning sky.

Image credit: TRAPPIST/E. Jehin/ESO