Jupiter Facts

General Facts & History

Planet Jupiter

Jupiter has been known to humanity since antiquity due to it being visible to the naked eye. However, it was believed to be a star by ancient peoples and only within the last several hundred years was it realized to be a planet.
The name Jupiter comes from the ancient Romans. In their mythology Jupiter was the king of the gods.
The discovery of four of Jupiter's moons by Galileo in 1610 was the first proof that there are celestial bodies orbiting something other than the Earth. This was strong evidence in support of Copernicus' Sun-centered model of the Solar System.

Jupiter is easily the largest planet in the Solar System in terms of size.
Jupiter's mean diameter is 139,822 km (86,919 miles)
It would take 11 Earths lined up side-by-side to stretch from one side of Jupiter to the other.
The volume of Jupiter is 1.431 x 10¹⁵ km³ (8.894 x 10¹⁴ miles³)
The number of Earths that would fit inside Jupiter is 1321.
Jupiter is the most massive planet in the Solar System.
Jupiter has a mass of 1.898 x 10²⁷ kg (4.184 x 10²⁷ lbs.)
Jupiter is the second most massive object in the Solar System after the Sun. It is over two times as massive as all of the other planets combined.
Jupiter's mass is 318 times that of the Earth's.
The escape velocity for Jupiter is 59.5 km/s (140,000 miles per hour).
If Jupiter had been 80 times more massive nuclear fusion would have occured in its core. Thus Jupiter would have become a star rather than a planet.

Jupiter Compared to Earth

Jupiter is the fifth planet from the Sun in the Solar System.
On average, Jupiter's orbital distance from the Sun is 7.78 x 10⁸ km (4.87 x 10⁸ miles), which is five times the distance between the Sun and Earth.
Jupiter's aphelion (the farthest point in its orbit) is 8.16 x 10⁸ km (5.07 x 10⁸ miles).
Jupiter's perihelion (the closest point in its orbit) is 7.41 x 10⁸ km (4.60 x 10⁸ miles).
Jupiter completes one full rotation about its axis every 10 hours, giving it the fastest rotational speed of any planet.
The area of Jupiter around its equator rotates faster than its polar regions by around five minutes. This produces a bulge at the equator, making Jupiter one of the least spherical planets in the Solar System.

Jupiter's Great Red Spot

Jupiter is composed primarily of gas. As a result, Jupiter lacks a surface in the sense that the rocky, inner planets do.
Jupiter's atmosphere is composed of 90% hydrogen and 10% helium. This composition is very close to that of the Sun's composition, bolstering the belief by scientists that Jupiter could have been a star if it had been more massive.
Jupiter's Great Red Spot is an enormous storm that has been raging for over 300 years. This storm is so wide that two Earth's would fit inside of it.
Jupiter's interior is made up of three layers: a core, a layer of liquid hydrogen, and layer of gaseous hydrogen.
The core is rocky, with some estimates placing its mass at 45 times that of the Earth.
The liquid hydrogen layer gives Jupiter most of its mass. It is electrically conductive, producing Jupiter's enormous magnetic field.

Jupiter's Moon Ganymede

Jupiter has over 60 known moons.
Jupiter's moons are broken into two classifications: the larger Galilean moons and the smaller moons.
The Galilean moons are named after Galileo who discovered them in 1610. These moons are Ganymede, Io, Europa, and Callisto.
Ganymede, the largest moon in the Solar System, is larger than the planet Mercury.
The numerous smaller moons are believed to be the fragments of a larger moon that broke apart as a result of a collision with another large body.
While it is not commonly known, Jupiter possesses a ring system similar to that of Saturn. Unlike Saturn's rings, however, Jupiter's ring system is composed primarily of tiny dust particles, making it very dark and faint.

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