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This website only lists information on modern-day comets and meteor showers. The book, however, thoroughly investigates how specific ancient impacts and near misses changed religious beliefs around the world.

Comet ISON

Discovery Date and Circumstances for Comet ISON (C/2012 S1)

Image of Comet ISON at the time of discovery

Discovery image of Comet ISON (C/2012 S1).

Credit: International Scientific Optical Network

Comet ISON spent the vast majority of its life in the Oort Cloud, in the far reaches of our solar system, until its stable orbit was disturbed by a passing star. For the first time in 4.5 billion years the comet traveled through the Kuiper Belt and entered the inner solar system where it could finally be spotted.

On September 24, 2012 the Minor Planet Center announced that we had a visitor between Jupiter and Saturn speeding toward the Sun. The comet was identified by astronomers Artyom Novichonok and Vitali Nevski in CCD images of the constellation Cancer taken on September 21. The images were taken by a camera, on September 21, which was attached to the 15.7-inch (0.4-meter) Santel reflector telescope belonging to the International Scientific Optical Network ("ISON"). The discovery by was officially designated C/2012 S1, but has become more commonly known as Comet ISON.

Established in 2004, the International Scientific Optical Network ("ISON") consists of 23 observatories in 10 countries. Its mission is to detect, monitor and track objects in space. The Keldysh Institute of Applied Mathematics, which is part of the Russian Academy of Sciences, manages ISON.

Italian astronomers at the Remanzacco Observatory quickly confirmed the discovery by Artyom Novichonok and Vitali Nevski.

After the announcement on September 24, 2012, "precovery" images were discovered. They were taken by the Mount Lemmon Survey on December 28, 2011 and Pan-STARRS on January 28, 2012. "Precovery" means that images were taken of Comet ISON prior to its discovery, but Comet ISON wasn't identified as a comet in those images.

At the time of its discovery, Comet ISON (C/2012 S1) had an apparent magnitude of 18, meaning it was 63,000 times fainter than the faintest star visible to someone with 20/20 vision, without the aid of a telescope or binoculars, under perfect viewing conditions.

Orbit of Comet ISON (C/2012 S1)

Comet ISON's orbit, as calculated by JPL/NASA, appears alongside its orbital path through the constellations from the perspective of someone living in Sydney, Australia. Click on icon in lower right corner to enter full screen mode.

Credit: Adapted from NASA/JPL and Stellarium

After its discovery, the orbit of Comet ISON was quickly determined by astrophysicists at the Jet Propulsion Laboratory (JPL) in Pasadena, California. It was announced that Comet ISON would reach its closest point to the Sun on November 28, 2013. On November 28, it would be within 800,000 miles (1.2 million km) of the Sun's surface. Not all comets get this close to the Sun. In fact, the vast majority do not come as close.

This close encounter with the Sun caused several astronomers to predict that Comet ISON will be one of the brightest comets in history - even brighter than the full moon. The reason for these bold predictions is simple. Although Comet ISON is composed of several elements, like all comets, its primarily made of ice.

The Sun's temperature and solar wind causes the ice to melt as it enters the inner solar system. Ice and other materials begin to fall off the comet's nucleus, usually between the orbits of Mars

and Jupiter. These materials form the comet's coma and tails. Its the coma and tails, which allow the comet to be spotted by astronomers or telescopes which automatically scan the skies to detect asteroids and comets.

This melting increases the closer a comet gets to the Sun. It was especially so, when Comet ISON entered the Sun's corona and attempted to survive temperatures in excess of 1,000,000 degrees Fahrenheit (555,000 degrees Celsius). If it didn't disintegrate, it would shed an enormous amount of material. It could rival the brightness of the full moon. If it did, it could inspire people around the world to forget about Kim Kardashian or the price of Tesla shares and learn more about these amazing celestial visitors.

Unfortunately, the nucleus did not survive its close encounter with the Sun. It was declared dead by the European Space Agency on November 28, 2013. A small piece of the comet "came back to life" on November 29 and was detected by STEREO-A and the Solar Heliospheric Observatory (SOHO). However, it faded quickly and the remnants were invisible to the naked-eye after sunset. Although Comet ISON disappointed the general public, the coordinated study of Comet ISON by multiple space agencies and astronomers was incredible. The data gathered will advance our understanding of comets.

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