Comet Siding Spring’s encounter with Mars

Star charts showing the movements of Comet Siding Spring and Mars at the time of the encounter on 19th October 2014

Comet Siding Spring & Mars ephemeris
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SAST     Comet Siding Spring                 Mars
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19:30 17 37 33.94 -24 51 42.4    17 37 22.28 -24 51 29.3
20:00 17 37 33.81 -24 50 58.5    17 37 26.29 -24 51 31.4
20:28 17 37 33.69 -24 50 17.7    17 37 30.04 -24 51 33.4
21:00 17 37 33.56 -24 49 31.0    17 37 34.32 -24 51 35.6
21:30 17 37 33.43 -24 48 47.2    17 37 38.33 -24 51 37.7
22:00 17 37 33.30 -24 48 03.5    17 37 42.34 -24 51 39.8
————— ————————————————————————    ———————————————————————

MARS AND C/2013 A1 (SIDING SPRING) ENCOUNTER:

by Kos Coronaios

C/2013 A1 (Siding Spring), an Oort cloud comet discovered by Robert H. McNaught on the 3rd January 2013 at Siding Spring Observatory. The orbital period of this comet is several million years inbound and around 1 million years outbound.

Next perihelion is on the 25^th October, but a few days earlier the comet will pass extremely close to Mars. Calculations show that on the 19th October it could pass as close as 0.00088 AU’s, (132 000 km) from the center-point of Mars. For comparison, Mars’s outer moon Deimos orbits at 24 000 km from the planet and our Moon orbits the Earth at an average distance of 384 400 km. It will pass Mars at a relative velocity of 56 km/s reaching an estimated magnitude of -6 as seen from Mars.

Comet Siding Spring won’t put on a show for viewers here on Earth. But the fleet of robots at Mars, which includes five operational orbiters and two working rovers, could send some nice pictures of the encounter back home.

Presently (6^th October) the comet is at around Vm +11.5 in the star-field of the Milky Way heading towards Mars. It’s journey thus far has seen it pass some beautiful stars and clusters as well as a galaxy.