Comets do this when they are heated by the sun in outer space. You will begin to see the comet expelling gas jets. This is where the dry ice has turned to gas and needs to escape through small holes in the frozen water. Sometimes, this kind of gaseous exhaust will actually cause a comet's orbit to shift slightly. Over the next few hours, the comet will become cratered and it will get smaller.
Comets lose a little mass every time they go by the sun and blow off gas and dust.
All rights reserved.