According to Space.com
, Vitali Nevski and Artyom Novichonok of the International Scientific Optical Network (ISON) near Kislovodsk, Russia, discovered comet C/2012 S1 (ISON) on 21 September via images taken with a 40-centimeter reflecting telescope. The International Astronomical Union's Minor Planet Center in Cambridge, Massachusetts confirmed the discovery and announced it on 24 September.
According to National Geographic
, astronomers say the comet is now approximately 615 million miles (990 million kilometers) from Earth, between the orbits of the two giant planets Saturn and Jupiter. Preliminary reports say the orbit will make its closest (perihelion) approach to the Sun on 28 November, 2013 at a distance of 0.012 AU (1,800,000 km; 1,100,000 mi) from the center-point of the Sun. Astronomers say the comet will pass approximately 1,100,000 kilometers (680,000 mi) above the Sun's surface.
reports C/2012 S1 is expected to pass at about 6.2 million miles/10 million kilometers (0.07 AU (10,000,000 km; 6,500,000 mi) from Mars on October 1, 2013. This will allow NASA's Curiosity rover on Mars opportunity to snap pictures.
Astronomers at the Remanzacco Observatory, Italy have assured that the comet is not on collision course with Earth. They say C/2012 S1 "will get to within 0.012AU of the Sun at the end of November 2013 and then to ~0.4AU (about 37 million miles) from Earth at the beginning of January 2014."
However, it remains uncertain where the comet came from, although its orbit suggests it may have its origin in a spherical cloud of comets surrounding the solar system called the Oort Cloud
where there are billions of other comets in orbit. Raminder Singh Samra of the H.R. MacMillan Space Center in Vancouver, Canada, said: "For astronomers, these distant origins are exciting because it allows us to study one of the oldest objects in the solar system still in its original, pristine condition."
C/2012 S1 was observed close to Saturn and may still be observed with powerful telescopes as a faint glow in the constellation Cancer. It is expected to become visible to the naked eye beginning in 2013.
According to National Geographic
, predictions of its orbital trajectory indicate that if it survives its close approach to the Sun, the comet will be brightest in the sky in November 28, 2013 as it moves away from the Sun. It will be visible during December after sunset and in the morning sky before sunrise. New Scientist
reports that scientists at the Remanzacco Observatory say that by December 9 it should be about as bright as Polaris, the North Star, and should remain visible to the naked eye until mid-January 2014. According to Astronomy Now
, the comet could become brighter than the full moon around its closest approach to the Sun.
Astronomers say that the orbit of C/2012 S1 is similar to that of the Great Comet of 1680
, one of the brightest in history. Space.com
reports that the Great Comet of 1680 was very bright in the sky and was visible even in daylight, throwing off a bright tail that spanned the western twilight sky. Some astronomers say that given the close orbital relationship between C/2012 S1
and the Great Comet of 1680, the objects may be the same.
reports that Samra, says "if it lives up to expectations, this comet may be one of the brightest in history." According to The National Geographic
, the brightness of C/2012 S1, will depend on how much gas and dust is blasted off the central core of ice and rocks at its close approach to the Sun.The bigger the cloud and tail, the more reflective the comet, astronomers say.
However, Samra cautions: "While some predictions suggest it may become as bright as the full moon, and even visible during the day, one should be cautious when predicting how exciting a comet may get. Some comets have been notorious for creating a buzz but failing to put on a dazzling display. Only time will tell."
leaves a note for Mayan "doom-mongers":
"... and one last note to the Mayan death and doom-mongers: the universe apologizes but, despite its name, 2012 S1 is actually arriving in 2013 holiday season."