C / 2013 A1 (Siding Spring)

C / 2013 A1 (Siding Spring) ^[i]

Image taken by the Hubble Space Telescope on March 17, 2014
Properties of the orbit ( animation ) Epoch: February 3rd, 2014 ( JD 2,456,691.5)
Orbit type	hyperbolic See the chapter "Orbit"
Numerical eccentricity	1,00074
Perihelion	1,399 AU
Inclination of the orbit plane	129.0 °
Perihelion	October 25, 2014
Orbital velocity in the perihelion	35.6 km / s
history
Explorer	Robert H. McNaught , Siding Spring Observatory
Date of discovery	January 3, 2013
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

C / 2013 A1 (Siding Spring) is a comet from the Oort Cloud , which was discovered on January 3, 2013 by Robert H. McNaught at the Siding Spring Observatory with the help of a Schmidt telescope . It was subsequently recognized that images had already been taken on December 8, 2012 by the Catalina Sky Survey . The time of its discovery, the comet was 7.2 AE from the sun away.

Mars flyby

A preliminary orbit determination based on observations up to February 25, 2013 showed a slim chance that the comet would hit Mars on October 19, 2014 .

This did not happen, because on October 19, 2014 at 8:29 p.m. CEST , the comet was moving past Mars at a relative speed of 56.0 km / s (201,000 km / h) at a distance of about 140,800 kilometers. The flyby was observed from space and Mars by at least 16 devices, including the Hubble Space Telescope , the Mars rover Curiosity and the MAVEN spacecraft .

Orbit

Based on observations over a period of 2 years, an orbit could be determined for the comet that is inclined by around 129 ° to the ecliptic . The comet thus runs in the opposite direction (retrograde) like the planets through its orbit. At the point of the orbit closest to the sun ( perihelion ), which the comet passed on October 25, 2014, it was located at a distance of 209.2 million km from the sun in the area between the orbits of Earth and Mars . Already on September 5th it had reached the closest approach to earth with 0.89 AU / 133.3 million km. On October 19, it passed Mars at an extremely short distance of only 140,800 km (about a third of the distance between Earth and Moon ) and on November 29, it passed Venus at a distance of 135.2 million km. There are no further approximations <1 AU to the planets .

The comet approached the sun with an orbital eccentricity very close to 1, i.e. on an extremely elongated ellipse with a semi-major axis of over 30,000 AU. This is probably a "dynamic new" comet from the Oort cloud that is crossing the inner solar system for the first time. Since the comet is currently still in the inner solar system , it is not yet possible to calculate a definite future orbit for it. If you are still purely speculative based on a current railway solution, such as For example, if Farnocchia in the JPL Small-Body Database were to integrate it into the future with the Solex calculation program, then - but with insufficient consideration of non-gravitational effects - after leaving the inner solar system, an elliptical orbit with a large Semi-axis of about 4,900 AU and an orbital period of 350,000 years.