Jupiter is the fifth planet from the sun, and the largest planet in the solar system. It was named for the ruler of the gods in Roman mythology. Jupiter has 1400 times the volume of earth and is only 318 times more massive. The average density of Jupiter is one-fourth of earth's, showing that it consists of gas rather than rocks and metals like other planets.
Jupiter orbits the sun at an average distance 5.2 times greater than earth and makes a complete revolution in 11.9 earth years. It only takes 9.9 hours to rotate on its axis. The rotation is not always the same. The banded look of jupiter shows the presence of strong atmospheric currents that lead to different rotation periods at different latitudes. The bands are made much more apparent because of the soft pastel colors of the Jovian clouds, which includes the infamous Great Red Spot in the clouds. The colors of the clouds come from compounds formed by ultraviolet light, lightning discharges, and heat.
Knowledge of Jupiter increased in 1979 with the visits by the Voyager 1 and the Voyager 2 spacecrafts launched by NASA. Observations from earth showed that most of Jupiter's atmosphere is hydrogen and helium. The interior has the same composition which yields the low density.
When the dying comet Shoemaker Levy-9 crashed into Jupiter in 1994, scientists recived a lot of information. The collision heated up interior gases and brought them to the surface. Jupiter radiates twice as much energy it recieves from the sun. The source of this energy is a very slow gravitational contraction.
Jupiter's atmosphere is very cold. Since hydrogen is so abundant, hydrogen-based molecules like methane, ammonia, and water, are plenty. Temperature fluctuations in the atmosphere show a pattern of changing winds like in earth's equatorial region.
Although only the barest surface of Jupiter is visible, calculations show that temperature and pressure increases toward the center where hydrogen liquifies and then becomes a metallic, highly conductive state. A core of earthlike material is in the center. The Jovian cloud magnetic field is 14 times stronger than Earth's. Its polarity is opposite of Earth's.
So far, 16 satellites (moons) have been discovered. The four largest were discovered in 1610 by Galileo: Io, Europa, Ganymede, and Callisto. Io and Europa, which are close to Jupiter, are dense and rocky like the inner planets of the solar system. Ganymede and Callisto are farther away and are composed of water ice and have low densities.
Callisto is just as big as Mercury and Ganymede is bigger. If they orbited the sun, they would be considered planets. The bodies of these moons are marked by numerous craters, probably by comet fragments. These moons resemble thhe satellite of Earth.
The surface of Europa is very smooth. It is covered by a larger by a layer of water ice and a layer of liquid water is beneath it. A network of shallow cracks cover the surface. The Hubble Space Telescope in June 1994 detected a thin oxygen atmosphere on Europa, making it the fourth moon in the solar system to have a known atmosphere.
Io is one of Jupiter's most remarkable moons. It has a yellow, brown, and white appearance dotted by black features. Sulfur dioxide forms a transient atmosphere. The white regions are sulfur. The remaning moons are smaller and less studied. The outer eight come in two groups of four.
In conclusion, I think Jupiter is one of the most interesting and cool planets in our solar system. It's size makes it good topic to study. Jupiter is so famous, we even have cars and a city named after it!
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This page was written by Jessica in the astronomy class of BCC/Broward County on July, 1998 |