The name _planet_ is derived from a Greek word, (= planêtês=, _planetes_,) which signifies a _wanderer_, and is applied to this class of bodies, because they shift their positions in the heavens, whereas the fixed stars constantly maintain the same places with respect to each other. The planets known from a high antiquity are, Mercury, Venus, Earth, Mars, Jupiter, and Saturn. To these, in 1781, was added Uranus, (or _Herschel_, as it is sometimes called, from the name of its discoverer;) and, as late as the commencement of the present century, four more were added, namely, Ceres, Pallas, Juno, and Vesta. These bodies are designated by the following characters: 1. Mercury, [Planet: Mercury] 2. Venus, [Planet: Venus] 3. Earth, [Planet: Earth] 4. Mars, [Planet: Mars] 5. Vesta, [Planet: Vesta] 6. Juno, [Planet: Juno] 7. Ceres, [Planet: Ceres] 8. Pallas, [Planet: Pallas] 9. Jupiter, [Planet: Jupiter] 10. Saturn, [Planet: Saturn] 11. Uranus, [Planet: Uranus] The foregoing are called the _primary_ planets. Several of these have one or more attendants, or satellites, which revolve around them as they revolve around the sun. The Earth has one satellite, namely, the Moon; Jupiter has four; Saturn, seven; and Uranus, six. These bodies are also planets, but, in distinction from the others, they are called _secondary_ planets. Hence, the whole number of planets are twenty-nine, namely, eleven primary, and eighteen secondary, planets. You need never look for a planet either very far in the north or very far in the south, since they are always near the ecliptic. Mercury, which deviates furthest from that great circle, never is seen more than seven degrees from it; and you will hardly ever see one of the planets so far from it as this, but they all pursue nearly the same great route through the skies, in their revolutions around the sun. The new planets, however, make wider excursions from the plane of the ecliptic, amounting, in the case of Pallas, to thirty-four and a half degrees.