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The Solar System


Like planets, comets orbit the Sun.
Unlike a planet, the orbit of a comet is often
highly elliptical and may be very, very long.

A comet can only be seen when it is near
our solar system, close to the Sun.
At other times the comet is too far away to be seen.

The Orbit of a Comet

The speed of a comet changes during its orbit.
As the comet gets closer to the Sun,
the Sun's gravity pulls the comet towards it and the
comet gets faster. Also, the gravitational forces become
stronger as the comet gets closer to the Sun. The comet
is travelling at its fastest when it is closest to the Sun.

As the comet moves away from the Sun, the reverse
happens. The Sun's gravity pulls the comet backwards
and slows it down. The gravitational forces become
weaker as the comet gets further away. The comet is
travelling at its slowest when it is furthest from the Sun.

In energy terms, the movement of the comet is similar
to a swinging pendulum or bouncing ball.
When the comet is closest to the Sun,
it has its maximum kinetic energy
and minimum gravitational potential energy.

When the comet is furthest from the Sun,
it has its minimum kinetic energy
and maximum gravitational potential energy.

What is a comet?

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