Introduction

Jupiter is by far the largest planet in our solar system. The fifth planet out from the sun, it is thirteen hundred times larger than Earth, with three hundred times Earth's mass. Its diameter measures 85,000 miles (137,000 kilometers) across, while the Earth's diameter is just over 7,900 miles (12,700 kilometers) at the equator. With its sixteen moons, Jupiter is considered a mini-solar system of its own. Jupiter is often the brightest object in the sky after the sun and Venus. For an unknown reason, it reflects light that is twice as intense as the sunlight that strikes it. Through a telescope, Jupiter looks like a globe of colourful swirling bands. These bands may be a result of Jupiter's fast rotation. One day on Jupiter lasts only ten hours (compared to a rotational period of twenty-four hours for the Earth).

What is the core of Jupiter composed of?

Astronomers believe that Jupiter has a rocky core made of material similar to Earth, but with a diameter about five or ten times than that of Earth's core. The core's temperature may be as hot as 18,000 degrees Fahrenheit (10,000 degrees Celsius), with pressures two million times those at the Earth's surface. Scientists believe that a layer of compressed hydrogen surrounds the core. Hydrogen in this layer may act like a metal and may be the cause of Jupiter's intense magnetic field (five times greater than the sun's).

What is Jupiter's Great Red Spot?

Jupiter's most outstanding feature is its bright Great Red Spot. The spot is actually a swirling, windy storm over 8,500 miles (14,000 kilometers) wide and 16,000 miles (26,000 kilometers) long, an area enough to cover two Earths. Winds blow counterclockwise around the Great Red Spot at about 250 miles (400 kilometers) per hour. The spot may derive its red color from sulfur or phosphorus, but no one is certain. Beneath it lie three white oval areas. Each is a storm about the size of the planet Mars.

How was Jupiter formed?

One theory about the planet's origin is that Jupiter is made of the original gas and dust that came together to form the sun and planets. Since Jupiter is so far from the sun, its components may have undergone little or no change. A more recent theory, however, states that Jupiter was formed from ice and rock from comets, and that it grew by attracting other matter around it.

Could there be life on Jupiter?

Perhaps the biggest surprise uncovered by Galileo's mini-probe was the lack of water on Jupiter. Of course, overall conclusions can not be drawn from one sampling. But if it turns out that Jupiter is not the watery planet scientists have always assumed, then there is little chance of finding life there.

Why are astronomers today particularly interested in studying Jupiter?
One reason Jupiter is considered such an important object for study is that scientists believe it may hold information about the birth of the solar system. "Jupiter is a giant ruin left over from events we hardly understand," said astronomer Toby Owen of the University of Hawaii in late 1995. "It's like opening a tube that has been sealed for four and one-half billion years."

Back To Top