The Planet Jupiter


The Planet Jupiter is the LARGEST PLANET in our Solar System. Jupiter has at least 63 moons and they include: Europa, Io, Callisto and Ganymede.

Jupiter has been explored in flybys in the 1970s by NASA’s Pioneer 10 and 11 and Voyager 1 and 2 spacecraft. Galileo first orbited it and is currently being studied by Juno spacecraft.

The Planet Jupiter Photo

Facts about Planet Jupiter

* Diameter: 85,788 miles the largest planet – more than 12 Earths could line up across it

* Temperature: Range -163° C to >-121° C

* Distance from Sun: Approximately 466 million miles

* Atmosphere: Mostly hydrogen and helium

* Surface: A giant ball of mostly hydrogen and helium

* Rotation of its axis: 9 hours, 55 minutes in Earth time (the length of one rotation)

* Rotation around the Sun: 12 Earth years 

* Magnetic Field: Yes

* Number of Moons: 63 moons have been identified Ganymede is the largest moon – it is bigger than both Mercury and Pluto


The Italian scientist, Galileo Galilei was the first astronomer to view Jupiter through a telescope. While viewing Jupiter in January 1610, he observed four satellites orbiting the planet, which lent credence to the Copernican theory that the Earth and other planets revolve around the Sun.  Previously, many people held to the belief, developed by 2nd century astronomer, Ptolemy, that everything revolved around the Earth. Galileo’s discovery was a major step forward for astronomy. Jupiter’s satellites are mostly named for his mythological lovers.

The four satellites are known now as the Galilean moons. They are the four largest moons of Jupiter: Callisto, Europa, Ganymede and Callisto. These were the first group of objects found to orbit another planet.

In May 2002, astronomers announced an additional 11 moons for Planet Jupiter. All 11 are small bodies with diameters estimated to be between 2 and 4 kms. The moons are inclined, highly elliptical retrograde orbits with an average distance of 21 million kms from the giant planet. The number of moons now known to orbit Jupiter are 39 and makes it the planet with the most moons.

These discoveries have been possible by a new generation of electronic cameras that can scan wide areas of the sky and detect dim objects, making them very efficient tools to search for small moons.

Jupiter related Spacecraft:

Flights to Jupiter: The United States has sent seven space probes to Jupiter: (1) Pioneer 10 (December 1973) (2) Pioneer 11 (December 1974) (3) Voyager 1 (1979) (4) Voyager 2 (1979) (5) Ulysses (February 1992) (6) Galileo and (7) Juno (2016). ESA’s Jupiter Icy Moons Explorer launches in 2022. Also NASA’s Space Launch System may launch an Orbiter to Europa in 2020s.

First Jupiter Orbiter was NASA’s Galileo spacecraft. In December 1995, Galileo dropped a probe into Jupiter’s atmosphere, which collected the first direct measurements of the atmosphere.

Cassini made a flyby in 2000 on its way to Saturn. NASA’s New Horizons spacecraft made its flyby in 2007.

Comet Shoemaker-Levy 9

In March 1993, astronomers Eugene Shoemaker, Carolyn Shoemaker, and David H. Levy discovered a comet near Jupiter.

Astronomers witnessed a spectacular event when 21 fragments of a comet named Shoemaker-Levy 9 crashed into Jupiter’s atmosphere. The impacts caused tremendous explosions, some scattering debris over areas larger than the diameter of Earth.


Jupiter has three thin rings around its equator. They are much fainter than the rings of Saturn.

Jupiter can’t ever become a Star

Jupiter is the fastest spinning planet in the Solar System.

Magnetic Field

Jupiter’s magnetic field is 14 times as strong as Earth

You can see Jupiter with your own eyes

Jupiter is usually the fourth brightest object in the sky at night and in our in the Solar System. The three objects that are brighter than Jupiter are the Sun, the Moon and Venus. Occasionally, Mars sometimes appears brighter than Jupiter.


Approximately ninety percent of the upper atmosphere is hydrogen, and approximately ten percent of the upper atmosphere is helium.


Amazing as it may seem scientists have speculated that life on Jupiter is possible. This would occur beneath the cloud cover where room temperature conditions exist, these lifeforms would be airborne although this theory is thought to be highly speculative.


Because of the giant size of Jupiter, the gravity there is 2.4 times more than on Earth. If you weigh 100 pounds on Earth, you would feel like you weighed 240 pounds on Jupiter.

Distance From The Sun

Jupiter is almost 500 million miles from the Sun (483,780,000 miles). Earth is only 93 million miles from the Sun. Even though Jupiter is the largest planet in the Solar System, this is why it still looks so small.i

Great Red Spot

Great Red Spot is a continual anticyclonic storm. It’s located twenty two degrees south of the equator. The storm alone is actually larger than the planet Earth, or the planet Mercury. According to astronomers, there is evidence that the storm existed on the planet at least since 1831.

Did you know?

Scientists use the planet’s gravity to accelerate spacecraft so they can reach Saturn, Uranus and Neptune.


Jupiter Odyssey: The Story of Nasa’s Galileo Mission by David M. Harland

Shoemaker by Levy by David H. Levy

The Giant Planet Jupiter by John H. Rogers

The Planet Jupiter Links:

Pictures and Inormation on Jupiter:

Project Galileo: NASA’s JPL Home Page

Nine Planets’ Jupiter:

NASA/JPL’s Jupiter:

Jupiter Events:

The Planet Saturn Photo


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