Studies in Astronomy #264922

As my readers are doubtless aware, the solar system consists of a number of planets revolving round the sun as a centre, and of subordinate systems of satellites revolving round the planets, or at least round some of them. Our own earth is one of these planets, the third in order of distance from the central luminary, which forms the common source of light and heat to all the members of the system. In addition to the planets and satellites, there are also some comets which form permanent members of the solar system. Some of these comets revolve round the sun in very elongated orbits, while the planets and satellites revolve in nearly circular orbits. A consideration of the absolute size of this planetary system and its relative size compared with that of the universe of stars, or at least the universe visible to us, may prove of interest to the reader.