In fact, shooting stars are not stars at all. We call them meteors, and scientists believe that they are broken fragments of comets, which still move about in space when the comet itself does so no longer. We see them when they enter out atmosphere because they leave a trail of light behind them, caused by the friction of air on their surfaces. Most meteors are very small, but some can weigh several tons, and the vast majority of them disintegrate when they pass through the heat of the earth’s atmosphere. But some meteors, the larger ones, do land on earth, and when they do we call them meteorites. There are two main types of meteor – those made of minerals, which look like rock and are called aerolites, and those made chiefly of nickel and iron, which we can metallic meteors. Although it is very rare for a meteorite to fall on dry land, scientists think that many fall to earth every day, but that they land in the water which makes up two thirds of the earth’s surface. This is why we hardly ever notice when they do hit the earth.