Changes in Jupiters Surface within Human History Storms

As instruments improve and finer details on other planets can be seen, scientists are more often able to watch changes on the surfaces of other planets. The Moon's surface is largely unchanging, since it is no longer volcanically active, it has no atmosphere or large-scale weather, and there have been no recent large impacts onto its surface. Since the Moon often dominates mankind's images of other planets, it is tempting to think of other planets as cold, unchanging places in general. Planets like Jupiter and Saturn, though, have large heat outputs from their interiors and giant, changing magnetic fields, along with active gaseous atmospheres, and so there their surfaces change in ways that can be seen over time by mankind.

The Great Red Spot is a huge anticyclonic storm in Jupiter's southern hemisphere, around 20 degrees south latitude. Giovanni Cassini, the Italian astronomer, may have seen the Great Red Spot on Jupiter first around 1655, or Robert Hooke, the English experimentalist, may have seen it first in 1664.Though telescopes had only developed in the previous few decades to the point that the Great Red Spot could be resolved, there is a school of thought that the Great Red Spot itself first developed on Jupiter in the early 1600s. Early descriptions of Jupiter's cloud systems reported no spot, and it is a very prominent feature, so the reasoning goes that if it had been there in the earliest years of telescopic observation (beginning in 1608), it would have been commented upon. Some historians of science also

Jupiter's Great Red Spot is an immense anticyclonic storm that fluctuates in size, color, and position over time. (NASA/JPL/Voyager 2)

think that the first convincing report of the Great Red Spot was in 1831 by the scientist Heinrich Schwabe, and that the feature that Hooke described in 1664 was a different storm altogether.The image of the Great Red Spot shown here was taken by the Voyager 2 mission and also shows a white oval, directly beneath the Great Red Spot.

Though the Great Red Spot has remained active throughout at least the last 170 years, it does change visibly through time. The spot did not become truly prominent until the 1880s, which is when it developed its deep red color. Since then the color has continued to fluctuate, varying from deep red to pale salmon or buff, or even disappearing completely, leaving what is then called the Red Spot hollow. The Great Red Spot is now about 15,000 miles (24,000 km) in the east-west dimension X 8,750 miles (14,000 km) in the north-south dimension.Though even the current Great Red Spot is far larger than the planet Earth, which has a diameter of about 8,125 miles (13,000 km), the spot has been as large as 25,000 miles (40,000 km) in its east-west dimension. In addition to changing size, the spot wanders in position. Over a regular 90-day period, the Spot moves

White ovals are anticyclones smaller and more transient than the Great Red Spot.

(NASA/JPL/Galileo)

White ovals are anticyclones smaller and more transient than the Great Red Spot.

(NASA/JPL/Galileo)

1,250 miles (2,000 km) north and then 1,250 miles (2,000 km) south of its average latitude. The Great Red Spot also moves in longitude, and over the last hundred years has completed about three circuits back and forth around the planet.The latest observations from Galileo showed that the interior of the Great Red Spot is rotating more slowly than its edges, and that its very center may even have an area of circulation in the opposite sense from the rest of the spot.Throughout most of the spot, winds cycle counterclockwise, and at its edges, take about six Earth days to make one complete lap around the spot. Though wind speed and size show that this is a huge storm, there are still no satisfactory theories about its cause and duration.

Aside from the Great Red Spot, smaller-scale cyclones and anticyclones develop and fade away rapidly, on time scales of a few months. These tend to appear as white spots, where clouds are lacking. In 1938, in Jupiter's South Temperate Belt, three large anticyclonic ovals were first observed, and named the White Oval Spots. In the image above, the leftmost of the White Ovals is 5,600 miles (9,000 km) in breadth.They move relative to each other as the belts move, and over time have merged, as shown in the time series here. In both 1998 and 2000, two of the White Oval Spots merged into one. Since 2000, there has been only one White Oval Spot. Philip Marcus, a professor of physics at the University of California at Berkeley, has conducted computer models that predict global climate changes on Jupiter. Vortices like the White Spots transfer heat from Jupiter's equatorial regions to its poles. Eventually, the equator will heat by as much as

18°F (10°C) and its poles will cool by a similar amount. As shown in the lower color insert on page C-3, the extreme heat gradient will force vortices to form again and transfer heat to the poles.

Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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