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by Ron Kurtus (updated 18 January 2022)

Jupiter is the largest planet in our solar system. It is the fifth planet from the Sun, as compared with the Earth which is the third planet from the Sun.

Besides its large size, outstanding features of Jupiter include a huge storm on its surface—called the Great Red Spot—and the fact that it has 67 moons orbiting the planet. Exploration of Jupiter has been done with space probes and flyby missions.

Jupiter is named for the king of ancient Roman gods.

Questions you may have include:

This lesson will answer those questions.


Jupiter is the fifth planet from our sun and the largest planet in the solar system.


Jupiter has a radius of 69,911 kilometers (43,440.7 miles). It is 11 times wider than Earth. A comparison in size is if Earth were the size of a nickel, Jupiter would be about as big as a basketball.


The mass of Jupiter is 1.9*1027 kilograms, which is 318 times the mass of Earth.


Jupiter is 5.2 astronomical units (AU) away from the Sun. (1 AU is the distance from the Sun to Earth). This relates to an average distance of 778 million kilometers (484 million miles).

It takes sunlight 43 minutes to travel from the Sun to Jupiter.

Length of day

Jupiter has the shortest day in the solar system. One day on Jupiter—the time it takes for Jupiter to rotate or spin around once—is about 10 hours,

Length of year

The length of a Jupiter year—the time it takes to orbit the Sun—is equal to 4,333 Earth days or about 12 Earth years.


Since Jupiter's equator is tilted only 3 degrees with respect to its orbital path around the Sun, Jupiter spins nearly upright and does not have changes in seasons as extreme as other planets, such as Earth.


Outstanding features (called "Jovian" features) of Jupiter are its Great Red Spot and its numerous moons.

Great Red Spot

The Great Red Spot is a swirling oval of clouds twice as wide as Earth. It has been observed on the giant planet for more than 300 years.

Jupiter's Great Red Spot and swirling atmosphere

Jupiter's Great Red Spot and swirling atmosphere

(Picture taken by Hubble Space Telescope)


Jupiter is surrounded by 53 confirmed moons, as well as 14 provisional ones—for a possible total of 67 moons.

(See Jupiter's 67 Moons for more information.)

The four largest moons—Io, Europa, Ganymede and Callisto—are readily seen from Earth with a normal telescope. The other moons require an astronomical telescope or view from a space probe.

(See Jupiter's Galilean Moons for more information.)

Jupiter also has three rings, but they are very hard to see and not nearly as intricate as Saturn's.


Jupiter is the second brightest "star" in the night sky. Saturn is the brightest.


Jupiter is mostly made up of swirling hydrogen and helium gases and liquids, similar to the Sun. As a giant gas planet, Jupiter doesn't have a true surface., such that a spacecraft would have nowhere to land on Jupiter.


The Jovian magnetosphere is the region of space influenced by Jupiter's powerful magnetic field, which extends 1 to 3 million kilometers or 600,000 to 2 million miles from its surface. This enormous magnetic field is 16 to 54 times as powerful as that of the Earth.


While Jupiter has been known since ancient times, the first detailed observations of this planet were made by Galileo Galilei in 1610 with a small telescope. More recently, this planet has been visited by passing spacecraft, orbiters and probes.

In the 1970s, the Pioneer and Voyager spacecraft were the first to fly by Jupiter. In following years, the Galileo spacecraft orbited Jupiter and dropped a probe into its atmosphere. Then Cassini took detailed photos of Jupiter on its mission to neighboring Saturn, as did New Horizons on its way Pluto. The most recent mission was Juno, which arrived in the Jovian system in July 2016.


Jupiter is is the fifth planet from the Sun and the largest planet in our solar system. Outstanding features of Jupiter include a huge storm on its surface—called the Great Red Spot—and the fact that it has 67 moons orbiting the planet. Exploration of Jupiter has been done with space probes and flyby missions.

Astronomy can be fascinating

Resources and references

Ron Kurtus' Credentials


Jupiter: Overview - NASA

Jupiter - Wikipedia

Jupiter Facts -

Astronomy Resources


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