Watching dry ice sublimate (turn into gas instead of liquid) still manages to make me feel like a kid again. The kind of kid who is unsure of the difference between science and magic. Okay, not quite ... I’m old now and it’s impossible to ever look at things so innocently anymore. But when I see the carbon dioxide gas…
A mystery fluid is placed in a container and all the air is removed. The substance begins to freeze and boil at the same time. So what's going on?
The Atacama Pathfinder Experiment telescope, or APEX, is on Earth, but surrounded by ice spikes that make the landscape look decidedly alien. These "sculptures" are natural formations known as penitentes. And they form where it's very cold and very dry.
These mysterious ice figures form only at high altitudes, and only under very specific conditions. In the Andes, they're called "penitentes," and fields of them can stretch for miles.
All around the Martian south pole, there are huge deposits of frozen carbon dioxide, better known as dry ice. In this image by NASA's Mars Reconaissance Orbiter, we can see huge dry ice pits... and the mysterious walls that encircle them.