Hubble Telescope Captures Image of Comet ISON

by Nancy Atkinson on April 23, 2013

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NASA’s Hubble Space Telescope provides a close-up look of Comet ISON (C/2012 S1), as photographed on April 10, when the comet was slightly closer than Jupiter’s orbit at a distance of 386 million miles from the sun. Credit:NASA, ESA, J.-Y. Li (Planetary Science Institute), and the Hubble Comet ISON Imaging Science Team.

NASA’s Hubble Space Telescope provides a close-up look of Comet ISON (C/2012 S1), as photographed on April 10, when the comet was slightly closer than Jupiter’s orbit at a distance of 386 million miles from the sun. Credit:NASA, ESA, J.-Y. Li (Planetary Science Institute), and the Hubble Comet ISON Imaging Science Team.

Here’s our first good look at Comet (C/2012 S1) ISON. The Hubble Space Telescope captured this shot on April 10, when the comet was slightly closer than Jupiter’s orbit at a distance of 634 million kilometers (394 million miles) from Earth. Later this year, this comet could become a brilliant object in the sky, perhaps 10 times brighter than Venus.

Astronomers say preliminary measurements from the Hubble images suggest that the nucleus of ISON is no larger than 4-6 km (3-4 miles) across.


The astronomers said this is remarkably small considering the high level of activity observed in the comet so far. Astronomers are using these images to measure the activity level of this comet and constrain the size of the nucleus, in order to predict the comet’s activity when it will come with 1.1 million km (700,000 miles) of the Sun on November 28, 2013.

Even though Comet ISON was 620 million km from the Sun when this image was taken, the comet is already active as sunlight warms the surface and causes frozen volatiles to sublimate. A detailed analysis of the dust coma surrounding the solid, icy nucleus reveals a strong, jet blasting dust particles off the sunward-facing side of the comet’s nucleus.

The comet’s dusty coma, or head of the comet, is approximately 5,000 km (3,100 miles) across, or 1.2 times the width of Australia. A dust tail extends more than 92,000 km (57,000 miles), far beyond Hubble’s field of view.

Comet ISON belongs to a special category of comets called sungrazers. As the comet performs a hairpin turn around the Sun in November, its ices will vaporize in the intense solar heat. Assuming it defies death by evaporation, some predict it could become as bright as the full Moon. 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.

More careful analysis is currently underway to improve these measurements and to predict the possible outcome of the sungrazing perihelion passage of this comet.

ISON stands for International Scientific Optical Network, a group of observatories in ten countries who have organized to detect, monitor, and track objects in space. ISON is managed by the Keldysh Institute of Applied Mathematics, part of the Russian Academy of Sciences.

Source: NASA

About 

Nancy Atkinson is Universe Today's Senior Editor. She also is the host of the NASA Lunar Science Institute podcast and works with Astronomy Cast. Nancy is also a NASA/JPL Solar System Ambassador.

"Me" April 23, 2013 at 6:01 PM

Nice shot of ISON. Cannot wait when Webb T-S-Scope is shooting pics. They say the details will be so extraordinary. The delays of Web’s launch is so frustrating. 2014 is now 2018. Lost count of the delays they have had. Hope 2018 is it w/delays. PEACE!

Gyula Gubacsi April 24, 2013 at 9:41 AM

As far as I know, the Webb telescope won’t be optical telescope, but an infrared one. That is, it won’t give spectacular images for the human eyes, and won’t be too useful for solar system bodies. Even the Hubble isn’t the best tool for that.

"Me" April 24, 2013 at 3:08 PM

Yes. I have heard of infrared also. But I also have heard from a few colleagues working indirectly w/the WST it will also have optics. What that entails I have no clue. The delays are huge! The key is they have been “UPGRADING”. The tech gets better every tear the delays come up. So as far as I know from those few colleagues I know. Its changing monthly. Webb was supposed to be ready in 2014. Then 2015 etc…& now its 2018. It looks/sounds like an auction bidding what year it will be ready….lol. ..take care.

Gyula Gubacsi April 29, 2013 at 9:51 AM

It’s pretty common that the dead-lines for new, cutting-edge technology gets delayed. Frustrating or not, it is a territory that wasn’t attempted by anyone else before. So, while it would be great to have it up as soon as they can manage, in these topics patience is really important.

"Me" April 29, 2013 at 3:58 PM

Yes, patients is key. But as a human being. At times I don’t have too much at my older age. When I was in my mid 20′s(over 30+ yrs ago). I didn’t care too much about time. Now? Well. I’m in a bit of a hurry to see things getting down like yesterday. Its a older guy thing now ;-)… . ..take care.

Guest April 23, 2013 at 6:26 PM

Over the winter I did some upgrades to my telescope. Hopefully Comet ISON will be spectacular. I have all summer to look forward to and get my act together to produce some cool pics.

Aqua4U April 23, 2013 at 7:41 PM

Do you see flakes in the tail of the above Hubble image? This ‘first timer’ is shedding mass fast… Bright when found, it’s been shedding prodigiously from early on. Save some for us? (Original estimate was 50km dia… ha ha)

steve black April 24, 2013 at 5:29 AM

People get ready
There’s a comet coming
You don’t need no baggage
No telescope…

George Morales April 24, 2013 at 11:40 AM

It is shedding it’s mass so fast that by the time it gets near the sun, it is a goner.

Christopher Cone April 24, 2013 at 1:21 PM

A comet’s mass actually has very little to do with whether or not it survives an encounter with the Sun. It is true that a comet has to be a certain size and density to survive, but what is most important is what kind of material is closer to the core of the comet and how porous it is.

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