Does It Snow on Other Planets?

At the top of mountains on the planet Venus, underneath a layer of thick clouds, is a layer of snow. But this is not the kind of snow that brings skiers to mountains on Earth. The atmosphere on Venus is so hot that water-based snow doesn’t exist. Instead, the "snow-capped" mountains on Venus glitter with two types of metal: galena (lead sulfide) and bismuthinite (bismuth sulfide).

Scientists say that this so-called snow is probably more similar to frost. On the lower Venusian plains, temperatures reach a searing 480°C (894°F) -- hot enough so that the reflective pyrite minerals on the planet’s surface are vaporized, entering the atmosphere as a kind of metallic mist, and condensing on mountaintops.

Are there snow days in space?

• Maxwell Montes is the tallest peak on Venus, with an altitude of 11 kilometers (6.8 miles). That’s 3 kilometers (1.8 miles) higher than Mount Everest.
• More than 96 percent of the Venusian atmosphere is carbon dioxide, and Earth’s sister planet has nearly 100 times as much atmospheric gas.
• Snowflakes on Mars are smaller than their Earth counterparts -- roughly the size of a human red blood cell. They’re composed of carbon dioxide, not water.