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Space Station Info >> Nine Planets
Nine Planets
A planet is a body that directly
orbits a star, is large enough to be round because
of self gravity, and is not so large that it triggers
nuclear fusion in its interior. All the planets
revolve around the sun. There are nine planets
altogether- Mercury, Venus, Earth, Mars, Jupiter,
Saturn, Uranus, Neptune and Pluto. Among these
nine planets Mercury, Venus, Earth and Mars are
called "rocky" or "terrestial"
planets and the planets like Jupiter, Saturn,
Uranus and Neptune are called the "gaseous"
planets. A popular mnemonic used to remember the
planets in order is: My Very
Educated Mother
Just Showed
Us Nine Planets.
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It is not known with certainty
how planets are formed. The prevailing theory
is that, when a protostar forms from a condensing
nebula, the remnant of the nebula becomes
a thin disc of gas and dust that revolves
around the protostar. Localised mass concentrations
within this disc form increasingly dense
pockets of matter, which then collapse inward
under gravity to form planets. When the
star's core ignites its solar wind blows
away the remaining material, leaving a solar
system like our own. |
This theory is being greatly
challenged with the discovery of extrasolar systems
that vary greatly from our own.
View the details of the following planets
vMercury
vVenus
vEarth
vMars
vJupiter
vSaturn
vUranus
vNeptune
vPluto
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