In DepthPlanetary Science

Intruder from the Oort cloud will graze Mars

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Science  03 Oct 2014:
Vol. 346, Issue 6205, pp. 19
DOI: 10.1126/science.346.6205.19

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On 19 October, the comet Siding Spring will sideswipe Mars in a near miss that will be on display for five orbiting spacecraft, including two that just arrived last month. After cowering from high-speed dust in the comet's tail, the spacecraft will examine the comet and watch as its diffuse atmosphere collides with Mars. Unlike other comets that have been visited by spacecraft, Siding Spring hails from the Oort cloud, a distant holding tank for trillions of comets, and its orbit suggests that it is a first-time visitor to the inner solar system. Scientists are hoping to get a glimpse of the comet's nucleus, which would be a first for this class of comet.