Comet ISON

Solar system imager Damian Peach caught Comet ISON (C/2012 S1) at its best so far in this image made November 15 with a 4-inch Takahashi FSQ-106 refractor at f/5. He attached an SBIG STL-11000 CCD camera and took five 2-minute exposures through a luminance filter and single 2-minute exposures through red, green, and blue filters. The field of view is 2.5° wide.

Damian Peach

Two astronomers found Comet ISON (C/2012 S1) glowing dimly at magnitude 18.8 on September 21, 2012. On November 28 of this year, ISON will lie closest to the Sun — a scant 680,000 miles (1.1 million kilometers) from its surface. Latest predictions indicate that it will peak at magnitude –4.5, equivalent to the brightness of Venus.

Comet ISON is already visible through small- to medium-sized telescopes from a dark site, and binoculars and naked eyes will come into play as it nears opposition.

On December 8, Comet ISON crosses into the northern sky. It should shine brighter than 1st magnitude and perhaps sport a spectacular tail. Northern Hemisphere viewers will get increasingly better views as Christmas approaches.

Comet ISON reaches perihelion (closest to the Sun) November 28 and perigee (closest to Earth) December 26. // Astronomy: Richard Talcott and Roen Kelly

Observing Information

Comet ISON may have survived

Although many observatories couldn't see the comet after perihelion, NASA's Solar and Heliospheric Observatory observed a streak of material streaming away from the Sun. Learn more »

Comet ISON fizzles as it rounds the Sun

While the fate of the comet is not yet established, it is likely that it did not survive its trip. Learn more »

Comet ISON approaches the Sun

As the comet first appears to NASA's Solar and Heliospheric Observatory, Editor David J. Eicher shares the many ways you can celebrate the celestial visitor November 28. Learn more »

Comet ISON imaged by HSC November 5, 2013

Hyper Suprime-Cam captures a clear image of Comet ISONт??s long tails

The tails extend more than 1° from the Sun in the new photo. Learn more »

C/2012 S1 (ISON) taken November 20, 2013

MESSENGER captures images of Encke and ISON

Observations of ISON conclude on November 26, when the comet passes too close to the Sun, but MESSENGER will continue to monitor Encke with both the imagers and spectrometers through early December. Learn more »

Comet ISON captured November 22 and 23

Solar system imager Pete Lawrence of Selsey, England, took back-to-back images while in La Palma, one of Spain's Canary Islands. See the gallery »

Countdown to Comet ISON

Editors from Astronomy and Discover magazines discuss everything you need to know about his special celestial visitor. Watch now »

Comet ISON comes into solar observatory's view

The Solar Terrestrial Relations Observatory (STEREO) captured ISON and periodic comet 2P/Encke in its HI-1 camera November 21. Learn more »

Comet ISON peaks as it rounds the Sun

Senior Editor Richard Talcott describes how Comet ISON (C/2012 S1) will look from November 22 through 30. Learn more »

Comet ISON captured November 21

Astroimager Gerald Rhemann of Vienna, Austria continues to the image the comet, this time from Farm Tivoli, Namibia. See the gallery »

Comet ISON unfolds its wings

New images indicate that the comet has lost individual fragments in the past few days. Learn more »

Comet ISON imaged November 9 by Micro-Observatory

MicroObservatory catches Comet ISON

The comet recently brightened and is visible in the constellation Virgo. Learn more »

Optical image of the structures surrounding the nucleus of Comet ISON

Subaru Telescope captures visible-light images of comets ISON and Lovejoy

Astronomers captured the detailed structures of the envelopes of dust and gas surrounding the nuclei of both comets. Learn more »

Comet ISON captured November 17

Astroimager Gerald Rhemann took this photo from Ebenwaldhöhe, Lower Austria. See the gallery »

Comet ISON captured November 15

Solar system imager Damian Peach caught the comet at its best so far. See the gallery »

MESSENGER detects comets ISON and Encke

The Mercury-orbiting spacecraft has captured images of both comets, thus setting the stage for observations later this month when both will shine brighter and appear closer to the innermost planet. Learn more »

Comet ISON brightens during Novemberт??s third week

Senior Editor Richard Talcott describes how Comet ISON (C/2012 S1) will look from November 15 through 21. Learn more »

Comet ISON captured November 14

Photographer Harlan Thomas of Calgary, Alberta, Canada, took this photo telescopically. See the gallery »

Comet ISON captured November 12

Frequent contributor Gerald Rhemann took this image through an 8-inch f/3.6 astrograph. See the gallery »

Comet ISON captured November 10

Damian Peach from Selsey, England, took this image through a 4.3-inch refractor. See the gallery »

Comet ISON shines in November's second week

Senior Editor Michael Bakich describes how to view this bright comet during its first week of naked-eye visibility. Learn more »

Video: Observe Comet ISON at its best

Senior Editor Richard Talcott shares how to view what promises to be the brightest comet of 2013 and likely one of the two or three brightest comets of the 21st century — so far. Learn more »

Comet ISON captured October 29

Astroimager Gerald Rhemann took this shot of the comet while it traveled across southeastern part of the constellation Leo the Lion. See the gallery »

Comet ISON captured October 27

Frequent contributor Damian Peach captured the comet under the light of a Last Quarter Moon. See the gallery »

Comet ISON captured by Hubble on October 9

Comet ISON blazes into glory

This frozen ball of gas and dust puts on a show in the predawn sky before reaching peak brightness in late November as it skims above the Sun’s surface. Learn more »

The National Science Foundationт??s Comet ISON Photo Contest

Whether Comet ISON is a once-in-a-lifetime event, a great performer, or a run-of-the-mill comet, your picture of it could win a $2,500 prize. Learn more »

Watch Comet ISON move

Terry Hancock and Cliff Spohn created a time-lapse of the comet from October 21. Watch now »

Comet ISON captured October 18

John Chumack from Dayton, Ohio, took this image of the comet while it was near reddish Mars and blue-white Regulus. See the gallery »

NASA's Hubble sees Comet ISON intact

Multiple lines of evidence suggest that the comet's nucleus hasn't disintegrated, as some reports had predicted. Learn more »

Get the most from Comet ISON in late October

The comet has a fine encounter with a trio of galaxies in Leo as the month closes. Learn more »

Comet ISON captured October 8

long-exposure images also like this one from Adam Block show the comet’s greenish color. See the gallery »

Comet ISON captured October 6

Efrain Morales Rivera included negatives with his image of the comet in early October. See the gallery »

Comet ISON captured October 4

Astroimager Chris Schur reported that the comet was faint but distinctly visible through 8x50 binoculars when he shot this photo. See the gallery »

Comet ISON details emerge as it races toward the Sun

Observations indicate that the sudden exposure to strong sunlight when the currently dark side of the comet gets closer to the Sun could trigger huge outbursts. Learn more »

How to view Comet ISON in early October

Mars points the way to this celestial visitor as it brightens before dawn. Learn more »

Comet ISON captured September 24

Astroimager Damian Peach from Hampshire, England, captured the comet with his 17-inch corrected Dall-Kirkham reflector. See the gallery »

Comet ISON: The real story

Editor David J. Eicher responds to the naysayers and clarifies what we really know about how ISON will perform this fall. Watch now »

Catch Comet ISON with your camera

Be ready to photograph this special celestial visitor with these expert tips. Learn more »

Comet ISON captured September 16

After a month of trying, frequent contributor Chris Schur captured the comet through his 12.5-inch Newtonian reflector. See the gallery »

Easy-to-find objects in the 2013 autumn sky

As Senior Editor Michael E. Bakich explains in this video, Comet ISON will be a prime attraction as the temperatures drop. Watch now »

The Great Comet of 2013

This special issue gives you a front row seat for Comet ISON’s once-in-a-lifetime visit! You’ll find everything you need to know to experience what could be the brightest comet in decades at its best. Get it now »

An interview with comet ISON's co-discoverer

Artyom Novichonok answers questions about his interest in astronomy, his comet discoveries, and what it's like to find what could be the comet of the century. Learn more »

Hubble captures Comet ISON with stars and galaxies

Researchers with the Hubble Space Telescope released a new image of Comet ISON on July 25. This composite includes photographs taken through two filters. Learn more »

Hubble captures gas emission from Comet ISON

Images with Spitzer’s Infrared Array Camera indicate carbon dioxide is slowly and steadily “fizzing” away from the comet, along with dust. Learn more »

Hubble keeps an eye on Comet ISON

The Hubble Space Telescope captured Comet ISON on May 8 as the solar system interloper was 403 million miles (649 million kilometers) from Earth, between the orbits of Mars and Jupiter. See the time-lapse video »

April 27 — Efrain Morales Rivera

Frequent online contributor Efrain Morales Rivera shot Comet ISON as it traversed the constellation Gemini. See the gallery »

Hubble captrues Comet ISON

The comet, which the Hubble Space Telescope imaged April 10, is already active as sunlight warms the surface and causes frozen volatiles to sublimate. Learn more »

Swift sizes up Comet ISON

Using images acquired over the past two months, astronomers have made initial estimates of Comet ISON’s water and dust production and used them to infer the size of its icy nucleus. Learn more »

March 2 — Pat Knoll

Astroimager Pat Knoll created this image of Comet ISON by combining shots at the beginning and end of a session through the 22-inch William Kuhn Telescope at the Orange County Astronomers Observatory near the town of Anza, California. See the gallery »

February — Dean Salman

Arizona astroimager Dean Salman imaged Comet ISON and several galaxies through a 20-inch telescope from Kitt Peak National Observatory. See the galery »

Deep Impact spacecraft eyes Comet ISON

The Comet ISON imaging campaign is expected to yield infrared data and light curves, which are used in defining the comet’s rotation rate, in addition to visible-light images. Learn more »

Is Comet ISON the comet of the century?

John Chumack shoots the comet in January as it glows dimly at magnitude 16. Check it out »

Will Comet ISON be a superstar?

Check out the January 2013 issue of Astronomy for a complete rundown of what might be the comet of the century. Buy it today »

Comet ISON will light up the sky

Two astronomers, Vitali Nevski from Vitebsk, Belarus, and Artyom Novichonok from Kondopoga, Russia, discovered the comet on images they obtained September 21. In late 2013, Comet C/2012 S1 (ISON) probably will become the brightest comet anyone alive has ever seen. Learn more »