Astronomy Fun Fact #57
When astronomers talk about ice in space, we're rarely talking about water ice.
Every material has a temperature where it becomes solid, and when a material usually exists in gas or liquid forms, its solid state is called ice.
Around a star, we call the distance where a molecule turns to ice its "snow line." The position of this snow line depends on the type of molecule and temperature of the star.
For most simple molecules in our solar system, the snow line is 450 million miles away from the Sun.