NASA's MAVEN spacecraft observes Comet Siding Spring during its encounter with Mars.
On October 19, 2014, Mars will receive a first-time visitor from the outer fringes of the solar system. C/2013 A1, better known as Comet Siding Spring, has been traveling toward the inner solar system for millions of years, and will just miss Mars by a distance of 88,000 miles on October 19 (roughly one-third of the distance from the Earth to the Moon). These animations depict the flyby as seen from orbit above Mars, and as seen from the Martian surface. The blue portion of Comet Siding Spring's tail is composed of ionized gas swept away from the Sun by the solar wind. The gray portion is composed of heavier dust particles, which are moving at 33 miles per second relative to Mars.
This artist's concept simulates a ground-based view of Comet Siding Spring at its colsest approach to Mars. Victoria, a Martian crater previously visited by NASA's Opportunity rover, is visible in the foreground.
A still image of the above artist's concept. The image is available in small and medium resolution versions, and a large-resolution version suitable for print. The original Photoshop file is also included.