The solar system contains the 4 inner, terrestrial planets of Mercury, Venus, Earth, and Mars, which are basically balls of rock and metal. By contrast, the 4 outer, gas giant planets of Jupiter, Saturn, Uranus, and Neptune are essentially giant balls of gas and liquid.

The five visible planets consisting of Mercury, Venus, Mars, Jupiter, and Saturn have been known since ancient times, and can easily be seen from Earth. Following the invention of telescopes, William Herschel discovered Uranus in 1781, and in 1846 John Couch Adams discovered Neptune. Pluto was located in 1930 by Clyde Tombaugh, but has since been relegated to a ‘dwarf planet.’

Explore the planets of our solar system below:

Gallery of Solar System Planets