Jupiter and its Galilean Moons
By: Logan Brink
April 19, 2011
The solar system is an intriguing place. There are objects in our solar system that have unfathomable beauty; a few of these beautiful objects being Jupiter and its four Galilean moons. Jupiter is one of the most interesting bodies in the solar system, so it makes sense that its four largest moons are equally fascinating. The Galilean moons are some of the most curious bodies in our solar system. From dead worlds to water worlds to fire worlds, these four moons may hold a lot of answers to some of the mysteries of the solar system.
At 5.2 A.Us (Astronomical units – 93,000,000 miles) from the Sun, Jupiter is the fifth planet from the Sun and the first of the gas giants (Bennett et. al A-14-15). Being so far away from the Sun, it takes Jupiter about 11.9 Earth years to orbit the Sun (Kerrod 148). Jupiter is the largest planet in the solar system; in fact, it is more massive than all the other planets combined! At its equator, the gas giant measures 88,850 miles in diameter (Kerrod 148). Jupiter is so huge that it is eleven times bigger across than Earth. Jupiter’s size, however, does not seem to have any effect on how fast the planet spins on its axis. Earth spins on its axis in about 24 hours, one Earth day. Jupiter has eleven times the diameter as Earth and spins on its axis in approximately 9 hours and 55 minutes (Kerrod 148). This means that the massive planet is spinning inordinately fast, this, as one can imagine, causes some pretty intense weather with 300-500 mile per hour winds. Jupiter’s most impressive feature is probably its massive hurricane type storm people know as the Great Red Spot. The Great Red Spot (GRS) measures 25,000 miles across (Kerrod 148). It is red because of the phosphorous in the atmosphere (Kerrod 148). Astronomers have been observing the Great Red Spot for 300-500 years (Kerrod 148). The GRS lies in the South Equatorial Belt and, for the most part, stays in the same spot (Kerrod 148). Hovering about five miles above the surrounding cloud tops, the GRS is spinning counterclockwise, making its way around the center in approximately six days (Kerrod 148). Because there are no oceans, mountains, or land on Jupiter, there is nothing to slow the raging storm down, and it sustains enough energy to keep going (astronomyonline). Along with the GRS, Jupiter also has interesting white ovals that surround the Great Red Spot. The white ovals are much less persistent than the GRS and come and go as they please. They only last a couple of months before they are replaced by another white oval (Kerrod 148). According to David Eicher of NASA, a semi-new discovery has been made on Jupiter – the Red Spot Jr. This is the second largest storm on Jupiter and it is as big as about 70% of Earth’s diameter (Eicher para. 5). Along with the massive storms on Jupiter, the planet holds another beauty, its ring system. Though not nearly as impressive as the rings of Saturn, Jupiter has a very faint, thin ring system surrounding the planet. Jupiter’s rings – like all ring systems – lie almost directly on the planet’s equatorial plane (Bennett et. al 342). The particles that make up the rings around are much less numerous than the particles that make up Saturn’s rings (Bennett et. al 342). The particles are also much less bright and often smaller that Saturn’s ring particles (Bennett et. al 342). Jupiter’s atmosphere is what makes it truly beautiful to look at. The massive planet’s atmosphere is about 1000 km thick (astronomyonline). Jupiter has three layers of clouds because of the different gases at different altitudes in Jupiter’s atmosphere (Bennett et. al 325). The top layer is composed of ammonia that has condensed into a cloud, the second layer is condensed ammonium hydrosulfide, and the bottom layer is condensed water (Bennett et. al 325). The clouds form the fascinating patterns people love to observe. All over Jupiter, there are...
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