High in the sky above Mars, it is snowing right now. Very gently snowing. The snow does not settle on the rubble-strewn land below – not these days, anyway – but instead vaporises into the thin atmosphere long before it reaches the ground.
The first flakes of snow, on a planet that until fairly recently was believed to be waterless, were spotted just a few months ago. A Nasa lander near the planet’s north pole was scanning the sky with a laser when it noticed the telltale signs of snowfall. The probe, called Phoenix, announced the news in a radio signal that was picked up by an overhead orbiter and beamed back to Earth. Nothing like it had ever been seen before.
