As we head into winter, many people will see these frosty figures show up on their windows, or on the hoods of their cars. And though you’re seeing them here on earth, such patterns are excellent examples of how ice forms in outer space.
We’ve been hearing a lot about water in space lately. Metaphorical buckets of water are stored, on the moon and on Mars, in the form of ice deposits. And we know that ice is zooming around space on comets, or condensing in giant clouds. The question is, how does all that water group together? If you took a glass of water into space, it wouldn’t freeze—at least not right away. First it would boil, as the lack of outside pressure allowed the water to break free of the tenuous cohesive forces between molecules.
When these molecules break free, they take a lot of the kinetic energy (otherwise known as the heat) in the water with them, causing the temperature in the remaining water to drop until the water freezes.
However, there is another phenomenon that creates ice in the universe, and you see in the morning when you scrape down your car windows.
Desublimation is also know as deposition. It happens when water molecules skip the liquid stage before turning to ice. Usually this happens when they encounter some other molecule to attach themselves to—often dust or salt. Huge icy clouds, and some impressive icy deposits, form in space just like this. Tiny water vapor molecules, drifting in space, find other molecules to attach themselves to and build up.
So when you’re despondently chipping away at your windshield with an old ATM card, just think of the cosmic majesty of all that space ice forming in outer space.