In a gas, the particles (atoms and molecules) have weak attractions for one another. They are able to move freely past each other with little interaction between them. The particles of a gas are much ...

Save guides, add subjects and pick up where you left off with your BBC account. Particles - molecules or ions - in a liquid and a gas are constantly moving randomly. Because of this movement ...

When stars die they eject particles and gases in dramatic supernovae or glow for millennia as majestic planetary nebulae. Ejected dust and gas from ... of dust attract one another in low gravity ...

Heat always spontaneously flows from a hotter place to a colder one – so says the second law of thermodynamics. But within an extremely sparse gas, the opposite may be possible, with heat ...