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Comet ISON's close pass

Already visible from Earth with a pair of powerful binoculars, Comet ISON will make its closest approach to the sun on November 28, 2013, when it will come within 1,150,000 miles of it.

If ISON survives its close call with the sun's extreme heat, NASA expects the comet to put on a spectacular show for Earth during the first weeks of December as it continues streaking through the sky, before making its closest approach to our planet on December 26, 2013 at the relatively close cosmic distance of 39.9 million miles.

It appears as if ISON may already be falling apart a bit. But if it survives the flyby, the potential exists for this to be one of the brighter comets of the past century.

You can even stage your own Thanksgiving Day comet watch with an ISON tracking app, aptly called "Comet Watch," which is available for free for the iPhone or iPad.

Updated:Caption:Photo:NASA/MSFC/Aaron Kingery
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Comet ISON was first discovered in September of last year by Vitali Nevski and Artyom Novichonok. It was first observed using the 16-inch reflector of the International Scientific Optical Network, or ISON.

This new view of ISON was taken with the TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) national telescope at ESO's La Silla Observatory on the morning of November 15, 2013.

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

This Comet ISON Observation Campaign is the hub for up-to-date information about Comet ISON, and gives you the latest data and links to relevant observatories and programs.
Updated:Caption:Photo:TRAPPIST/E. Jehin/ESO
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Bright Comet ISON

Comet ISON, lighting up the sky in the early morning hours of November 19, 2013, is seen here in a 10-second exposure taken with the Marshall Space Flight Center 20-inch telescope. The camera used for this image is black and white, but the smaller field of view allows for greater zoom on the head of the comet.

If ISON does survive its close encounter with the sun, the Slooh virtual observatory will be tracking the comet's path from telescope observatories in Arizona, South America, and the Canary Islands.
Updated:Caption:Photo:NASA/MSFC/MEO/Cameron McCarty
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Composite image of ISON

Taken on November 19, 2013, this image shows a composite "stacked" image of Comet ISON. These five stacked images of 10 seconds each were taken with the Marshall Space Flight Center telescope in New Mexico. This image stacking method allows the comet's tail to be better exposed in relation to the brighter head.
Updated:Caption:Photo:NASA/MSFC/MEO/Cameron McCarty
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Comet ISON streaks toward the sun

Comet ISON shows off its tail in this 3-minute exposure taken on November 19, 2013, using a 14-inch telescope at the Marshall Space Flight Center.

The stars in this image are seen as trails because the telescope is tracking the comet to keep it in focus, causing the stars to blur during the minutes-long exposure.

At the time this image was taken, Comet ISON was some 44 million miles from the sun -- and 80 million miles from Earth -- moving at a speed of 136,700 miles per hour.
Updated:Caption:Photo:NASA/MSFC/Aaron Kingery
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ISON during its closest approach to Mercury

NASA's Messenger spacecraft took this image of Comet ISON during its closest approach toward Mercury on November 20, 2013 using the Wide Angle Camera of the Mercury Dual Imaging System. The spacecraft is the first ever to orbit the planet Mercury; its seven scientific instruments are examining the history and evolution of the solar system's innermost planet.
Updated:Caption:Photo:NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/Southwest Research Institute
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Image from Stereo-A's Heliospheric Imager

NASA's Stereo-A spacecraft is monitoring ISON as it approaches the sun. This image from the spacecraft's Heliospheric Imager shows, going left to right, Comet ISON, Mercury, Comet Encke, and Earth late on November 21, 2013. The sun sits outside of the field of view of this camera to the right, with a coronal mass ejection spilling into the right side of the photo.
Updated:Caption:Photo:Karl Battams/NRL/NASA STEREO/CIOC
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ISON passing the plane of Mercury

This still image from the video shows Comet ISON just passing the plane of Mercury, with Comet Encke ahead and slightly above on November 22, 2013. The sun is located off-screen to the right.
Updated:Caption:Photo:Karl Battams/NRL/NASA STEREO/CIOC
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Comet ISON as seen by Stereo

A screen capture from the latest movie from the Stereo-A spacecraft's Heliospheric Imager shows the comet on November 25, 2013.
Updated:Caption:Photo:Karl Battams/NRL/NASA STEREO/CIOC
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NASA's Hubble sees ISON intact

A new image of Comet ISON rocketing toward the sun suggests that the nucleus of the icy comet remains intact, despite concerns from scientist that as it heats up and moves closer to the sun, it may begin to disintegrate. If the nucleus had broken apart, then Hubble would have likely seen the evidence of multiple fragments trailing out behind.

In this composite image which uses two filters, the comet's coma appears a greenish-blue color due to gas, while the tail is reddish due to dust streaming off the nucleus. The tail forms as dust particles stream out from the center. The comet was inside Mars' orbit and just 177 million miles from Earth when photographed here.

NASA expects Comet ISON to make its closest approach to Earth on December 26, 2013 at the relatively close cosmic distance of 39.9 million miles.
Updated:Caption:Photo:NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
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