Jupiter & Saturn
Jupiter & Saturn
Jupiter�is the largest planet in our solar system. It has a�mass that is greater than the masses of all the other planets in the solar system added together. Astronomers call Jupiter a gas giant�because the planet consists mostly of hydrogen and helium, and have no solid surface. When seen with the unaided eye, Jupiter has a pale orange color. Viewed through a telescope or in images taken by spacecraft, Jupiter appears as a globe covered with swirling, brightly colored clouds of brown, orange, white, and yellow.
Jupiter lies at the center of a system of cosmic objects so vast and diverse that it resembles a miniature solar system. The planet has 16 moons that measure at least 6 miles in diameter and dozens of smaller satellites. Four faint rings of dust particles circle the planet. Jupiter also has a strong�magnetic field. A magnetic field is the area around a magnet in which its energy can be detected. Jupiter's magnetic field extends beyond the planet throughout a huge region of space called the magnetosphere. Astronomers sometimes refer to the planet together with its rings, satellites, and magnetosphere as the Jovian system. Astronomers have made detailed observations of Jupiter for centuries. It was one of the first planets studied by the famous Italian astronomer Galileo in the early 1600's. Beginning in the 1970's, several spacecraft have explored the Jovian system in great detail. Like all the planets in our solar system, Jupiter travels around the sun in an�elliptical�(oval-shaped) orbit. Jupiter's orbit is nearly circular. It lies about five times as far from the sun as Earth's orbit does. The average distance between the sun and Jupiter measures around 484 million miles. Jupiter's orbit is tilted by 1.3 degrees from the�ecliptic plane, the imaginary plane that contains Earth's orbit. Jupiter takes nearly 12 Earth years to orbit the sun. Jupiter rotates faster than any other planet, taking about 9 hours 55 minutes to turn completely on its axis. This is the length of a day on Jupiter.
The planet's rapid spinning causes it to bulge slightly at the equator. Its diameter at the equator measures 88,846 miles, while the distance between its�geographic poles the ends of its axis measures only 83,082 miles. Jupiter, like Earth, has seasons. Jupiter's mass is about 318 times as great as the mass of Earth, but about 1,000 times smaller than that of the sun. Jupiter's average density is about 1.3 times as great as the density of water at room temperature. This density is much lower than the density of Earth. Jupiter's low density indicates that it is composed mostly of light elements rather than rock. The actual temperature of Jupiter varies with altitude and location, but because of its great distance from the sun, Jupiter is much colder than Earth. Scientists have different ways of discussing the temperature of gaseous planets...