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Red Spots and Shadowed Rings
Jupiter is renowned for its Great Red Spot, the giant, red anticyclone that Galileo observed through his telescope 400 years ago. An anticyclone is a high-pressure storm similar to a hurricane on Earth, except that hurricanes are low-pressure storms. The Voyager 1 spacecraft, in 1979, determined that the storm clouds churn at around eight kilometers above the other clouds. The vortex rotates counterclockwise with a period of six days.
In 2000, a second spot was discovered near the Great Red Spot. At first, the new spot was white, but it turned red in 2006, inspiring astronomers to call it Red Spot Junior. Because of this change in color, scientists were left wondering why Jupiter's spots are red. It is hypothesized that the clouds are formed from a reddish sulfur or phosphorous compound roused by the raging storm.
But, as of May 2008, scientists discovered there were three red spots on Jupiter--the new spot was dubbed the Baby Red Spot. Unfortunately, Baby Red did not live long: the Great Red Spot slowly ripped the smaller spot in two from June to July. However, it is possible that the little spot could regenerate because a surviving blotch has appeared on the other side of the Great Red Spot.
Voyager 1 not only watched the Great Red Spot as the craft approached Jupiter, but it also discovered that the largest gas planet had rings. It is understandable that the rings are not as nicely visible as Saturn's rings because the particles, created from collisions between meteorites and Jupiter's moons, are only the size of particles in cigarette smoke.
From 2002 to 2003, the Galileo spacecraft collected data on Jupiter's rings as it intentionally dove towards the planet to its death. Scientists have been analyzing the information and realized that when the rings' particles face the sunlight, they are positively charged, while particles in the Jupiter's shadow are negatively charged. This means that the shadow can change the shape of the rings. Professor Douglas Hamilton from the University of Maryland explains that the "different charges react differently to Jupiter's magnetic field, leading to changes in particle orbits, and when conditions are right, even the tilt or inclinations of the ring particles change."
It is suspected that the rings of the other planets may experience this phenomenon, but the process is more noticeable around Jupiter. Saturn's rings could be too immense to be significantly changed by the charged particles. This new evidence is intriguing because it potentially helps explain the birth of the planets, which started as a disk of dust and gas, slowly orbiting around and around.
* Read more about rings--the rings of Uranus!
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