User:TheAustinMan/sandbox/Comet ISON
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Comet ISON, formally designated as C/2012 S1,[nb 1] was a highly anticipated sungrazing comet that largely broke up during its perihelion in late November 2013 after reaching naked eye visibility in mid-November of that year. The comet was discovered on 21 September 2012 by Vitali Nevski (Виталий Невский, Vitebsk, Belarus) and Artyom Novichonok (Артём Новичонок, Kondopoga, Russia) using the 0.4-meter (16 in) reflector of the International Scientific Optical Network (ISON) near Kislovodsk, Russia, and later confirmed by unaffiliated observers. Early projections indicated that the comet would pass very close to the sun, and given its unusually distant discovery position beyond the orbit of Jupiter, would become very bright. In addition, its trajectory suggested that ISON had likely originated from the Oort cloud and would be making its first traversal of the Inner Solar System. Several observing campaigns were formed and several spacecraft were set to periodically observe the comet in premonition for its approach. Following discovery, the comet was precovered in images taken as far back as December 2011. Though the comet's nucleus was initially estimated to be much larger, more refined estimates indicated that ISON's nucleus was smaller than 0.8 km (0.5 mi) shortly before perihelion.
![]() Comet ISON as imaged by TRAPPIST on 15 November 2013 | |
Discovery | |
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Discovery date | Vitaly Nevsky and Artyom Novichonok at ISON-Kislovodsk, Russia using a 0.4-m reflector (D00) |
Orbital characteristics | |
Epoch | 14 December 2013 (JD 2456640.5) |
Perihelion | 0.01244 AU (q) |
Eccentricity | 0.9999947 1.0002 (epoch 2050) |
Orbital period | Ejection trajectory (epoch 2050) |
Max. orbital speed | 680,000 km/h (420,000 mph) |
Inclination | 62.4° |
Last perihelion | 28 November 2013 |
For the first few months following discovery, the comet remained well below the threshold for naked eye visibility but was dispersing an unusually large amount of dust and other materials. Throughout the first half of 2013, spacecraft and ground observatories regularly observed ISON, though the comet was lost in the sun's glare for Earth-based observers from June to August 2013. After reemergence, Comet ISON continued to steadily brighten, but for a period of time beginning in October brightening stagnated, indicative a decrease in material output. However, in mid-November, ISON suddenly went through an outburst, brightening by roughly two magnitudes and becoming visible to the naked eye. The comet steadily brightened in the following days, and entered the field of view of SOHO imagery on 27 November. Despite continued brightening, the comet did not brighten as much as previously forecast, and at the time of perihelion, dimmed slightly and could not be imaged up by the Solar Dynamics Observatory; as such the comet was largely believed to have disintegrated in the sun's corona. However, images later revealed that at least portions of the comet's nucleus remained intact after perihelion. These remnants later diffused into a cloud of cometary matter. Regardless of whether or not ISON remains an intact nucleus, its associated remnants are currently in a hyperbolic trajectory and are not expected to return to the Inner Solar System.