The Solar System consists of 2 kinds of planets:

  The Terrestrial planets include Mercury, Venus, Earth, and Mars. These are Earth-like planets that are small, dense, rocky worlds with less atmosphere than Giant planets.

 The Jovian planets include Jupiter, Saturn, Uranus, and Neptune. They do not have a solid surface and consist mainly of hydrogen and helium gas. Pluto does not really fit either category.

Density is a key measure of the material which comprises a planet. It is a measure of how much matter is packed into a volume of space. Terrestrial planets have high density (4-6) gm/cm3, Jovian planets have low density (1-1.5) gm/cm3

 

Planets also rotate and revolve .   Planets spin on their axis or rotate . The period of rotation determines the length of a day. The inclination of a planet's rotation axis will determine its seasons. Planets also revolve about the Sun. The period of revolution determines the length of a year for that planet. Planets further from the Sun revolve more slowly than those closest to the Sun.

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Typical features on the surfaces of planets and moons:

Impact Craters

Volcanoes

Ice

Rivers

Mountains

 

 

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