Could it ever snow on Mars?

Asked by: William Glynn, by email.

Yes. In fact, snow has already been detected falling on Mars – though up in its atmosphere rather than settling on the ground. In 2008, NASA’s Mars Phoenix Lander detected snow falling from clouds about 4km (13,000ft) above the planet’s surface. However the snow vaporised before hitting the ground. The snowy revelations came from a laser detector on Phoenix.