Coming soon Comet Siding Spring will reach its closest approach to Mars. October 19th the comet will be roughly 82,000 miles (132,000 km) from Mars which is about one third the distance from Earth to the Moon. Comet Siding Spring will come closer to Mars than any known comet flyby has ever come to Earth.
Comet Siding Spring originated from the Oort Cloud which is a spherical region that is 5,000-100,000 times farther away from the sun than earth is. The Oort Cloud is known to be the home of many other comets and other objects that have been there since the beginning of the solar system. Comet Siding Spring was within that Oort Cloud until something happened to give the comet a push towards the sun and the gravity of the sun has been pulling it in for over 1 million years and it is soon to reach Mars.
As comet Siding Spring approaches Mars it will have been close enough to the sun to form its coma and tail. This means that the comet will be ejecting dust and gases from it nucleus as it approaches Mars. Once it has gotten to its closest point to the planet the coma itself will be big enough that it will actually surround the entire planet. This means that the comet itself will not be close enough to go through Mars’ atmosphere but Mars will be going through the comets “atmosphere” that we call the coma. During the time that Mars is in the Coma there will be dust particles that will be travelling with the comet roughly 125,000 miles per hour colliding with Mars and everything orbiting it. NASA has planned for dust particles colliding with their spacecraft around Mars and decided that the ones that do not have enough protection will have to take the “duck and cover” approach which just means hide behind Mars and let it take the hits from the dust particles.
With all of this said the event should be a spectacular view from Mars and there are sure to be many pictures and data to be shared with all of the eyes pointing at the comet. For those of us here on the 3rd planet from the sun the comet is visible to those living south of the equator and is visible in the constellation Ophiochus. For those living north of the equator just enjoy the flood of images that will be coming our way soon from NASA.
To read more about this comet and its flyby of Mars please go to the NASA page about comet Siding Spring here: NASA – Comet Siding Spring