Comets are like "dirty snowballs"; frozen gasses with dust and rocks in them. Each pass near the Sun causes the comet's nucleus to be exposed to intense sunlight, which causes some tiny fraction of...
They are falling rocks. Literally. Gravity affects everything in the universe, and any rock will fall in a fairly predictable way under the influence of whatever large masses may be near. So if a...
In space, there is no natural medium, so there is no sound in space. Astronauts use electromagnetic energy to communicate because Electromagnetic energy does not need a medium.