Solar system

The solar system is the retinue of objects gravitationally bound to our Sun. Traditionally, it is said to consist of nine planets and their 156 (at last count) moons; however a large number of other objects, including asteroids, meteoroids, planetoids and comets orbit the Sun along with them.

Structure and layout of the solar system

The Sun (astronomical symbol ☉) is a spectral class G2 star that contains 99.86% of the system's mass; its two largest orbiting bodies, Jupiter and Saturn, account for 93% of the remainder.

Related Topics:
Sun - Astronomical symbol - Spectral class - Star - Mass - Jupiter - Saturn

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In broad terms, the charted regions of our solar system consist of the Sun, eight bodies in relatively unique orbits (commonly called planets or major planets) and two belts of smaller objects (which can be called minor planets, planetoids, meteoroids, planetesimals or, in the case of Pluto, planets). Objects in orbit round the Sun all lie within the same shallow plane, called the ecliptic, and all orbit in the same direction. Many are in turn orbited by moons, and the largest are encircled by planetary rings of dust and other particles.

Related Topics:
Planets - Major planets - Minor planet - Planetoids - Meteoroids - Planetesimal - Pluto - Ecliptic - Moon - Planetary ring

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The major planets are, in order, Mercury (☿), Venus (♀), Earth (♁), Mars (♂), Jupiter (♃), Saturn (♄), Uranus (♅/), Neptune (♆), and Pluto (♇), though Pluto's status has been thrown into question by the discovery of 2003UB313 (see below). All planets except Earth are named after gods and goddesses from Greco-Roman mythology (however, Earth is also called Terra, which is the name of the Roman goddess of earth).

Related Topics:
Mercury - Venus - Earth - Mars - Jupiter - Saturn - Uranus - Neptune - Pluto - 2003UB313 - Greco-Roman mythology - Terra

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Distances within the solar system are measured most often in AU, or astronomical units. 1 AU is the distance between the Earth and the Sun, or roughly 150 million kilometers. Pluto is roughly 38 AU from the Sun, while Jupiter lies at roughly 5.2 AU. For very large distances within the solar system, such as regions beyond Pluto or the orbital circumferences of planets, the terameter (Tm, one billion kilometers) is sometimes used.

Related Topics:
AU - Astronomical unit - Pluto - Jupiter - Terameter - Tm

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Despite the fact that many diagrams (like the at the top of this article), for practicality's sake, represent the solar system as having each orbit the same distance apart, in actuality the orbits are largely arranged geometrically, that is, each is roughly double the distance from the Sun as the one before it. Venus?s distance from the Sun is roughly double that of Mercury, Earth?s distance is roughly double that of Venus, Mars?s double that of Earth and so on.

Related Topics:
Venus - The Sun - Mercury - Earth - Mars

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