• Topic 1 Inner and Outer Planets

At times, the brightest object in the night sky is not the moon or a star. It is Venus, one of Earth’s closest neighbors in space. On a clear night, Jupiter might appear to be a large, bright star in the night sky. But in fact, Jupiter is one of the outer planets in our solar system.

  • The four inner planets are the closest to the sun. In order from closest to farthest, the inner planets are Mercury, Venus, Earth, and Mars. Inner planets have rocky surface, smaller in size and have fewer or no moons at all. Mercury and Venus have no moons, Earth has 1 Moon, and mars has 2 moons.
  • Jupiter, Saturn, Uranus, and Neptune are the outer planets. The outer planets are also called the gas giants, because they are huge and made up mostly of gases. Outer planets support ring system and have multiple moons.
  • Mercury is the closest planet to the Sun and has shortest orbit. Neptune is farthest from Sun and has longest orbit.
  • Venus is the hottest planet of the solar system and Neptune is the coldest planet.