By Dr. Lisa Will
This Sunday, October 19, Mars will have a close encounter with Comet Siding Spring.
And by close, I mean close!
Comet Siding Spring, also known as C/2013 A1, will be approximately 82,000 miles away from Mars at its closest approach. That might not seem like much, but to give you a sense of scale that is equivalent to about one-third the distance between the Earth and the Moon!