Exploring The Planets: Jupiter

New Horizons spacecraft took this collection of images of Jupiter and Io in 2007. Io is a volcanic moon that revolves around

Jupiter. Photo from: NASA.

The fifth planet from the sun and the solar system’s largest planet by far is Jupiter. This planet

is bigger than all the other planets in our solar system put together. It travels around the sun at

an average distance of about 483 million miles.

Jupiter was named for the ruler of the ancient Roman gods, the equivalent of the ancient

Greek god Zeus. The ancient Romans did not know how large the planet is, but the name

turned out to be fitting.

The planet is also one of the brightest objects in the night sky. Even a small telescope can

reveal its multicolored stripes, which are bands of clouds being pushed around the planet by

strong east-west winds. Jupiter is a world of complex weather patterns. Its most prominent

feature is an orange-red oval called the Great Red Spot, a long-lasting storm system that is

bigger across than Earth.

By Encyclopaedia Britannica, adapted by Newsela staff on 08.28.17

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Physical Features

An outer planet, Jupiter is much farther from the Sun than Earth and the other inner planets

are. Its orbit lies between the main asteroid belt and Saturn’s orbit. Its inner planetary

neighbor, Mars, orbits between the asteroid belt and Earth. Like the other outer planets —

Saturn, Uranus and Neptune — Jupiter is much larger and less dense than Earth and the

other rocky inner planets.

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Jupiter is so huge that it could contain more than 1,000 Earths. Its diameter, or distance

through its center, is about 89,000 miles. It is a kind of planet called a gas giant. It consists

almost entirely of gases, mainly hydrogen and helium, and has no solid surface. Photographs

of Jupiter actually show its layers of clouds, not a surface. These clouds appear as colored

spots and bright and dark stripes.

Deep inside Jupiter is an area of hot, thick liquid. The planet’s center may reach temperatures

of 45,000 degrees Fahrenheit. Surrounding the planet is a system of thin rings, which consist

of tiny rocks and dust. They are much smaller and dimmer than the planet Saturn’s rings.

More than 60 moons orbit Jupiter, most of which are very small. However, Jupiter has four

very large moons, named Io, Europa, Callisto and Ganymede. Ganymede is larger than the

planet Mercury. Scientists believe that Europa, Callisto and Ganymede may have water ice

beneath their surfaces.

Orbit And Spin

Like all planets, Jupiter has two types of motion: orbit and spin. Jupiter orbits, or travels

around, the sun very slowly. It takes about 12 Earth years to complete one orbit. In other

words, a year on Jupiter lasts about 12 Earth years.

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Jupiter also spins rapidly about its center. The planet takes less than 10 hours to complete

one rotation. That is how long a day lasts on Jupiter.

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Observations And Exploration

People have observed Jupiter from Earth since ancient times. Scientists sent the first

unmanned spacecraft to the planet in the 1970s. The spacecraft, called Pioneer 10 and 11

and Voyager 1 and 2, flew by the planet and collected information about it.

Later, the unmanned U.S. Galileo spacecraft orbited Jupiter. In 1995, it dropped an object

called a probe toward the planet. The probe sailed through the upper layers of Jupiter’s gases

and measured their properties. It was the first man-made object to make contact with a gas

giant.

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