The Solar System
The Solar System consists of the
Sun and those celestial objects bound to it by gravity.
These objects are the eight planets and their 166 known
moons, four
dwarf planets and billions of small bodies, including
asteroids, icy
Kuiper belt objects,
comets,
meteoroids, and
interplanetary dust.
Broadly, the charted regions of the Solar System are the Sun, four
terrestrial inner planets, the
asteroid belt, four
gas giant outer planets, the Kuiper belt, the
scattered disc, and ultimately perhaps the hypothetical
Oort cloud.
A flow of plasma from the Sun (the
solar wind) permeates the Solar System.
This creates a
bubble in the
interstellar medium known as the
heliosphere which extends out to around the scattered disc.
In order of their distances from the Sun, the eight planets are:
Mercury,
Venus,
Earth,
Mars,
Jupiter,
Saturn,
Uranus, and
Neptune.
As of mid-2008, four smaller objects are classified as dwarf planets:
Ceres is in the asteroid belt, while the other three (
Pluto,
Makemake, and
Eris) all orbit the Sun beyond Neptune.
Six of the planets and two of the dwarf 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.
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Our Sun
The Sun is the
star at the center of the
Solar System. The
Earth and other matter (including other
planets,
asteroids,
meteoroids,
comets and
dust) orbit the Sun, which by itself accounts for about 99.8% of the Solar System's
mass.
Energy from the Sun, in the form of sunlight and heat, supports almost all life on Earth via
photosynthesis, and drives the Earth's
climate and weather.
The diameter of the Sun measures about
1.4 million kilometers, which means that you could put 109 Earths around it at the
equator.
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