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The Solar System

What is a Planet?

A planet is a natural satellite of a star. There
are eight planets in our solar system.
All of the planets in our solar system orbit the Sun.

The planets themselves do not give out light.
We can see some of the planets in the night sky
because they reflect sunlight (like our moon does).
The planets are so far away that they appear to
us like dots of light. They look to our eyes like stars.

The orbit of a planet is almost circular. All of the
planets (except Mercury) orbit in the same plane.

The picture below shows the solar system.
The relative size of the planets is indicated
but the Sun is very much larger than shown.

The picture also shows Pluto in an elliptical orbit.
Pluto is a dwarf planet.
Click on a planet for more information.

Solar System

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