Comet Siding Spring makes close pass by Mars

Mars flyby illustration

Spacecraft orbiting Mars hunkered down behind the planet to safely observe comet Siding Spring's close approach, as shown in this illustration. (Spacecraft are not to scale.)


Mars and its squadron of spacecraft have emerged unscathed after being buzzed by comet Siding Spring.

On October 19, the comet whizzed past the Red Planet at a little more than 20,000 kilometers per hour. At its closest, Siding Spring was only 139,500 kilometers, roughly a third the Earth-moon distance, from the planet’s surface, meaning it probably put on quite a show for rovers like Curiosity. Other spacecraft were also eyeing Siding Spring from a safe location behind the Red Planet.

Data from the probes will be beamed back to Earth over the next few days and could give astronomers their most detailed look yet at a comet from the far-off Oort cloud.

For more on spacecrafts’ close encounters with comets, read SN‘s feature, “Rosetta readies for its close rendezvous with a comet.”

Ashley Yeager is the associate news editor at Science News. She has worked at The Scientist, the Simons Foundation, Duke University and the W.M. Keck Observatory, and was the web producer for Science News from 2013 to 2015. She has a bachelor’s degree in journalism from the University of Tennessee, Knoxville, and a master’s degree in science writing from MIT.

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