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INTRODUCTION TO THE SOLAR SYSTEM


The Solar System consists of our Sun, the planets and their moons, and the other objects that exist orbiting the Sun.

The Solar System is orbiting the Milky Way, our Galaxy. At the same time, the Planets and other objects in the Solar System orbit the Sun. Meanwhile, each Planet spins on its own axis or rotation.

The Sun
The Sun is a star, and although of vital importance to us on Earth, when compared with other stars in the Universe, it is actually just an average star in size, temperature and brightness.

Of course in our Solar System, it dominates, and is the source of all the heat and light for all the planets, as well as keeping them all in orbit using its gravitational force.

It is very bright from Earth, and observers should be extremely careful not to observe the Sun directly, either through a telescope or binoculars, or even with the naked eye, as it is so bright that looking at it directly can cause permanent damage to your eyes.

The Inner Planets
The four innermost planets are Mercury, Venus, Earth and Mars. They are collectively known as the Inner planets, Inner rocky planets or even terrestrial planets. The Earth is the largest of these inner planets.

Mercury and Venus do not have any Moons of their own, the Earth has one (The Moon, or Luna) and Mars has two Moons known as Phobos and Diemos.

The planets Mercury and Venus, because they orbit nearer the Sun than Earth, are also known as inferior planets.

Beyond the orbit of Mars lay many asteroids and some dwarf planets in an area known as the Asteroid Belt. The asteroids are also known as minor planets.

The Outer Planets
Beyond the asteroid belt are the Outer planets of Jupiter, Saturn, Uranus and Neptune. These are giant gas planets, much larger than the Earth, and consisting mainly of hydrogen and helium gas. These four also have rings around them, and Saturn's rings can easily be seen from the Earth. These planets also have many many moons each.

The largest of Jupiter moons are known collectively as the Gallilean Moons. Their names are Io, Europa, Ganymede and Callisto. They can been seen through a telescope to move around Jupiter over the course of days, Callisto taking just under 17 days to orbit Jupiter.

These Outer planets are also known as Superior planets as they orbit the Sun beyond The Earth.

Beyond the Outer Planets
At the edge of the Solar System beyond the Orbit of Uranus, is a cloud of comets and minor planets, including Pluto, which was formerly thought to be a planet but recently was discovered to be just one of many thousands of similar minor planets in this region, known as The Ort Cloud. This region extends half way to the nearest star beyond our Solar System.

Observing the Planets

See:
» Observing the Planets

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