Portal:Astronomy/Featured/April 2007
From Wikipedia, the free encyclopedia
The Solar System or solar system comprises the Sun and the retinue of celestial objects gravitationally bound to it: the eight planets, their 162 known moons, three currently identified dwarf planets and their four known moons, and thousands of small bodies. This last category includes asteroids, meteoroids, comets, and interplanetary dust.
In broad terms, the charted regions of the Solar System consist of the Sun (astronomical symbol 
), four rocky bodies close to it called the inner planets, an inner belt of rocky asteroids, four giant outer planets and a second belt of small icy bodies known as the Kuiper belt. In order 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 every planet past the asteroid belt is encircled by planetary rings of dust and other particles. The planets other than 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, (no symbol), which lies beyond the Kuiper belt in a region called the scattered disc.
Recently featured: Globular cluster – Binary star – Barnard's Star
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