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Saturday, June 30, 2007

Solar System

Solar System consists of the Sun and the other space objects gravitationally bound to it: the eight planets, their 162 known moonsthree currently recognized dwarf planets (including Pluto) and their four known moons, and billions of small bodies. This last group includes asteroids, Kuiper belt objects, comets, meteoroids and interplanetary dust.

In wide terms, the charted regions of the Solar System consist of the Sun, four terrestrial inner planets, an asteroid belt composed of small rocky bodies, four gas giant outer planets, and a second belt, called the Kuiper belt, collected of icy objects. Beyond the Kuiper belt lies the scattered disc, the heliopause, and eventually the hypothetical Oort cloud.

In sort of their distances from the Sun, the planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Six of the eight planets are in turn orbited by natural satellites, usually termed "moons" after Earth's Moon, and each of the outer planets is encircled by planetary rings of dust and other particles. All the planets apart from Earth are named after gods and goddesses from Greco-Roman mythology. The three dwarf planets are Pluto, the largest known Kuiper belt object; Ceres, the largest object in the asteroid belt; and Eris, which lies in the scattered disc.

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