Planet Facts

There are 8 planets in our solar system, they are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. With the exception of Neptune and Uranus the other 6 planets can be seen unaided and all 8 are visible with a small telescope or binoculars.

Order of the Planets

The Order of the Planets

  • The order of the planets from closest to the Sun outwards is; Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and finally Neptune.
  • The largest planet in the solar system is Jupiter, followed by Saturn, Uranus, Neptune, Earth, Venus, Mars with the smallest being Mercury.

The table below shows the size of the planet, how far it is from the Sun and how long it takes to complete a single orbit.

NameDiameterDistance from the SunOrbit Period
Mercury4,879 km57,909,227 km (0.39 AU) 88 days
Venus12,104 km 108,209,475 km (0.73 AU)225 days
Earth12,742 km149,598,262 km (1 AU)365.24 days
Mars6,779 km227,943,824 km (1.38 AU)1.9 years
Jupiter139,822 km778,340,821 km (5.20 AU)11.9 years
Saturn116,464 km1,426,666,422 km (9.58 AU)29.5 years
Uranus50,724 km2,870,658,186 km (19.22 AU)84.0 years
Neptune49,244 km4,498,396,441 km (30.10 AU)164.8 years

What is a Planet?

Planets are among the many worlds and smaller objects that orbit the Sun. The formal definition of planet, as voted on by the International Astronomical Union in 2006, is as follows:

A planet is a celestial body that
(a) is in orbit around the Sun,
(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and
(c) has cleared the neighbourhood around its orbit.

Under this definition, Pluto is NOT a planet, but has been deemed a dwarf planet because it has not yet cleared its orbit. This definition is under discussion, particularly by members of the planetary science community, and it may yet be further refined.

Planet FAQ

  • How many planets are there in our solar system? There are 8 planets in our solar system.
  • What is the smallest planet? Mercury is the smallest planet.
  • What is the largest planet? Jupiter is the largest planet.
  • Which planet is closest to the Sun? Mercury is the closest planet to the Sun.
  • Which planet is farthest from the Sun? Neptune is the farthest planet from the Sun.
  • What is the coldest planet? On average Neptune is the coldest planet
  • What is the hottest planet? Venus is the hottest planet.
  • What are the inner planets? Mercury, Venus, Earth and Mars are the inner planets.
  • What are the outer planets? Jupiter, Saturn, Uranus and Neptune are the outer planets.
  • Which planets have rings? Jupiter, Saturn, Uranus and Neptune have rings.
  • Is there life on other planets? Not that has been encountered so far!

Facts about the Planets

Click on any planet below to find out more about it.