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The planet Jupiter imaged by NASA's Cassini-Huygens spacecraft

The Planet Jupiter imaged by the Cassini-Huygens spacecraft. Credit: NASA / JPL

Fifth planet from the Sun, Jupiter is by far the largest in the solar system. In the night sky, it’s brightness is exceeded only by our neighbors the Moon and the planet Venus. It is a gas giant planet which, as the name suggests, is primarily composed of gaseous hydrogen and helium in an atmosphere tens-of-thousands of kilometers deep.

Even though it is the largest planet in the solar system, Jupiter also has the fastest rotation, with a day lasting a little under ten hours. This means that the cloud tops at the equator are moving at around 43,000 kilometers per hour!

Jupiter is escorted through space by at least 67 known moons, the most famous being the four inner satellites known as the Galilean moons. Discovered in 1610, these moons are among the most massive bodies in the solar system, and are all larger than the dwarf planets.

Quick Stats:

  • Classification:  Gas Giant Planet
  • Equatorial Radius:  71,492 km   (11.2 x Earth)
  • Mass: 1.8986×1027 kg   (317 x Earth)
  • Sidereal Rotation Period: 9 hr 55 min
  • Orbital Period: 11.86 years
  • Orbital Distance: 5.2 AU (778,547,200 km)
  • Inclination: 1.3°
  • Eccentricity: 0.048
  • Axial Tilt: 3.13°
  • Density: 1.326 g/cm3
  • Surface Gravity: 2.528 g
  • Temperature: -108°C at Earth atmospheric pressure
  • Moons: 67

Factoids:

  • Jupiter is the largest planet in the solar system, and contains more matter than all of the other planets combined.
  • Jupiter is the third brightest object in the night sky after the Moon and Venus.
  • The diameter of Jupiter is roughly ten times that of the Earth, and roughly one-tenth that of the Sun.
  • Because Jupiter is mostly gaseous, the equator rotates faster at the equator than it does at the poles. This is known as differential rotation.
  • You could fit about one thousand Earths inside the volume occupied by Jupiter.
  • While Jupiter is mostly gaseous, it may have a solid core about the size of the Earth.
  • The pressure in the lower levels of Jupiter's atmosphere is so intense that some regions are thought to be composed of liquid, metallic hydrogen.
  • The Great Red Spot on Jupiter is an enormous storm about 2-3 times the size of the Earth, and has been observed for at least 350 years. It is a high-pressure anti-cyclone, which towers about 8 kilometers above the surrounding cloud tops.
  • The clouds on Jupiter are divided into distinct bands known as belts (lower altitude and darker colour) and zones (higher altitude and lighter colour).
  • Jupiter's magnetic field is extremely large and powerful. If it could be seen with the naked eye, it would be around six times the size of the full Moon. Any spacecraft passing close to Jupiter have to be shielded from this radiation.
  • The four Galilean moons are all larger than the dwarf planets. Ganymede, the largest moon in the solar system, is even larger than the planet Mercury.
  • Io orbits Jupiter in a region of intense radiation known as a plasma torus, which is composed of particles from Io's atmosphere that are ionized and swept up by Jupiter's magnetic field. This torus then co-rotates with the magnetic field at a speed of around 74 kilometers per second.
  • As Jupiter's magnetic field rotates and sweeps over Io, it generates an electric current between the planet and Io known as the Io flux tube.
  • Jupiter has a thin, dark system of rings that is composed mainly of dust.

Jupiter and Earth to Scale

Jupiter and Earth to scale

Jupiter and Earth to scale. Credit: NASA / JPL

The Planet Jupiter