Introduction

Whether we look at them with the naked eye or with the help of the largest telescope, the stars are just points of light. On the other hand, most of the planets appear as disks in a telescope of even modest power. This does not mean, of course, that the planets are larger than the stars, only that the planets are much closer to us. The sun, like other stars, glows brightly because it is extremely hot. The planets are too cool to shine by themselves and we see them by the sunlight they reflect. The sun together with its accompanying planets, their satellites, and other smaller bodies make up the solar system. The members of the solar system dwell in emptiness and are separated by vast distances from everything else in the universe.