A meteoroid recently slammed into the side of a hillside on Mars, exploding on impact, destabilising the slope and triggering a long avalanche. The crater only measures about five meters (16 feet) across, but the avalanche left a dark trail of dry dust stretching a full kilometre (0.62 miles) down the side of a slope in a hilly region of the red planet. The image was captured by the High Resolution Imaging Science Experiment – HiRISE – aboard NASA’s Mars Reconnaissance Orbiter spacecraft.
The close encounter between comet Siding Spring and Mars in October 2014 flooded the planet with an invisible tide of charged particles from the comet’s coma, according to data from NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft. The comet’s powerful magnetic field temporarily merged with, and overwhelmed, the planet’s weak field.