How are shooting stars formed? Are they harmful?
Shooting stars are not stars. They are called meteors. If a bit of dust or a rock moving about in the interplanetary space happens to encounter the earths atmosphere the collision is very violent because the relative velocity can be very high. The frictional force heats up the material with emission of bright light and evaporation of the material before it reaches the surface of the earth. A large number of such meteors hit the earth every day. Occasionally a big rock comes in that is not completely vapourised in the atmosphere. Its remnants can hit the earth and cause damage. In the history of the planet some very large impacts of this kind must have occurred and caused a major change in its morphology as also on the evolution of life on the planet.
