Astronomy and Space



First published on December 30, 2018

Planets are large sphere of material that orbit the Sun. Some planets are primarily rocky in composition. Others are primary liquid or gas. There are eight planets in our solar system:

  1. Mercury
  2. Venus
  3. Earth
  4. Mars
  5. Jupiter
  6. Saturn
  7. Uranus
  8. Neptune

The first four planets are known as terrestrial planets. They are Earth-like in that they are primarily composed of rock.

Mercury, Venus, Earth, Mars. Earth is shown with atmosphere and clouds.

Terrestrial planets (credit: NASA/Lunar and Planetary Institute)


The later four are known as Jovian planets, because they are similar to Jupiter (Jove). They are more voluminous than terrestrial planets. However, most of that volume comprises liquids and gasses.

Jupiter and Saturn shown lwith mostly gaseous interiors, Uranus and Neptune are mostly icy oceans

Gas interiors of Jovian planets (credit: NASA/Lunar and Planetary Institute)

There are also several large minor planets such as Pluto.



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