View Full Version : Sublimation of ice

2006-Mar-06, 05:40 PM
The article today about high pressure ice raises the question as to why ice doesn't sublimate in the vacuum of space. How can ice occur in comets, asteroids or even on our moon?

grant hutchison
2006-Mar-06, 07:29 PM
It does sublime. It just does so vanishingly slowly at sufficiently low temperatures. A metre thickness of ice will sublime into vacuum in just a 1000 years at 150 K, but will last a billion years at 110 K. (Figures from Icy Worlds of the Solar System, edited by Pat Dasch.)

Grant Hutchison

Kaptain K
2006-Mar-08, 07:45 AM
Which is exactly what happens to comets. As a comet nears the Sun, it warms up and sublimates like mad. After perihelion, it heads back into the cold outer reaches of the solar system, cools off and shuts down until the next time.