Exploring The Planets: Jupiter By Encyclopaedia Britannica, adapted by Newsela staff on 08.28.17 Word Count 691 Level 800L 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. Jupiter is the largest of the eight planets in our solar system and the fifth planet from the sun. It is bigger than all the other planets put together. Jupiter travels around the sun at an average distance of about 483 million miles. Jupiter was named for the ruler of the ancient Roman gods. He was the equivalent of the ancient Greek god Zeus. The ancient Romans did not know how large the planet was. The name turned out to be fitting, though. Jupiter is also one of the brightest objects in the night sky. Even a small telescope can reveal its multicolored stripes. These are in fact bands of clouds being pushed around the planet by strong winds. Jupiter is a world of complex weather patterns. Its most prominent feature is an orange-red oval called the Great Red Spot. This spot is actually a long-lasting storm system that is bigger across than Earth. This article is available at 5 reading levels at https://newsela.com. 1
Physical Features Jupiter is one of the four outer planets, along with Saturn, Uranus and Neptune. They are much farther from the sun than Earth and the other inner planets are. Jupiter lies between the main asteroid belt and Saturn. Like the other outer planets, it is much larger and less dense than Earth. Jupiter is so huge that it could contain more than 1,000 Earths. The distance through its center is about 89,000 miles. Jupiter is a kind of planet called a gas giant. It consists almost entirely of gases, mainly hydrogen and helium. The planet 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. This article is available at 5 reading levels at https://newsela.com. 2
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 Saturn s rings. More than 60 moons orbit Jupiter. Most of them 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 A year is the amount of time it takes a planet to make one full revolution around the sun. Earth takes just over 365 days to make a full trip, so that is the length of a year on Earth. A year on Jupiter lasts about 12 Earth years. That is because Jupiter is farther from the sun and takes longer to travel around it. This article is available at 5 reading levels at https://newsela.com. 3
Jupiter also spins rapidly about its center. A single day is equal to the time it takes a planet to make a full rotation. That is one complete spin on the planet's axis. Earth takes 24 hours to make one full rotation. Jupiter spins much faster, taking only 10 hours to complete one rotation. That is how long a day lasts on Jupiter. This article is available at 5 reading levels at https://newsela.com. 4
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 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. This article is available at 5 reading levels at https://newsela.com. 5