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Of all the planets,
we can sometimes see Mercury without telescopes and of course we
can easily see the Earth but we need a telescope to see the other
planets.
The three outer most planets are Uranus, Neptune
and Pluto.
Uranus
Uranus has rings like Saturn |
Uranus and Neptune are both fairly similar; they
are made of gas, very much like Jupiter and Saturn.
They both even have a ring system like Saturn although
not quite as amazing.
All of the planets go around the Sun following
a path that is like a squashed circle. They also all go around the
Sun in roughly the same plane.
That means that if the Sun were sitting at the
middle of a huge piece of paper, the planets would all be travelling
on the paper, never travelling to far above or to far below it.
As they move around the Sun, they are all spinning and they all
tend to spin in an upright way.
Think of the way a spinning top spins. Uranus is
different. Its almost rolling around the Sun on its side! We think
that at some time in the past, Uranus must have been knocked over
by some large rock smashing into it.
Neptune
Neptune, the eighth planet from the Sun is very
similar to Uranus and through a telescope looks blue.
Can you remember reading about Jupiter and its
Great Red Spot? Well, Neptune has a similar feature called the Great
Dark Spot and its just like Jupiter's spot but a little smaller
and darker in colour.
It's the same sort of thing too - a huge hurricane
system that's bigger than the Earth.
Pluto
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Pluto
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Pluto is a bit of a strange planet. The four planets
near the Sun are made of rock and you could walk around on the surface,
then the four next planets are made of gas and you could not walk
around on them.
Then there's Pluto. It's just like the four nearer
planets so it has got a solid surface. It's also got a very weird
path around the Sun. All the other planets move around the Sun in
paths like gently squashed circles.
Pluto on the other hand has a path that is like
a very squashed circle. It even takes Pluto inside the orbit of
Neptune on occasions so that Neptune is the most distant planet
for a while, not Pluto!
Astronomers have always been arguing whether Pluto
is a planet or not but I think it will always be thought of as a
planet.
We have now found two other 'planets' outside Pluto:
Sedna and Quaoar. They are both much smaller than Pluto so I think
they will not be officially called planets.
Got
a question on any of these planets? Ask Mark!
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