Volume: 04, Issue: 18 05/03/2006 
Jupiter rotates quickly, so its cloud bands divide into belts (darker colors) and zones (lighter colors). Other features, such as the Great Red Spot (left of center), appear within the bands. Image credit: NASA.
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This image shows the heavily cratered surface of Callisto. It was taken by Voyager 2 on July 7, 1979. An enormous impact basin with concentric rings is located near the top and slightly left of center. Image credit: NASA.
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This is one of the highest resolution images of Europa obtained by Voyager 2. It shows the smoothness of most of the terrain and the near absence of impact craters. Only three craters larger than 5 km in diameter have been found. Image credit: NASA.
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Other Articles in This Issue:
NASA Launches Satellites for Weather, Climate, Air Quality Studies
Galaxies Don Mask of Stars in New Spitzer Image
NASA Astronaut Eileen Collins Completes Career of Space Firsts
Rockets for Schools Rocket Launch 2006

Jupiter Shines

Jupiter puts on a great show as spring temperatures warm the United States.

Ascending to his throne, the king of planets rules May nights. The giant planet Jupiter reaches opposition – the point in its orbit opposite the Sun as seen from Earth – May 4, 2006. On that date, it appears bigger and brighter than at any other time this year. The planet lies in the southeast as darkness falls and will be the brightest object in the sky until Venus rises before dawn. Its bright, steady light and pale peach color may disguise Jupiter to some as a distant plane’s landing light.

Throughout 2006, Jupiter looms in front of the stars of the faint constellation Libra the Scales. For observers in mid-northern latitudes, this means the planet will not climb high in the sky. At opposition, Jupiter’s altitude maximizes at midnight CDT, when the planet stands about 40 degrees above the horizon (roughly halfway up in the sky) in the south.

Second only to the Moon, Jupiter ranks as the celestial object with the greatest observable detail. Even small telescopes show its four large moons, which appear as bright “stars” on either side of Jupiter. Usually seen in a straight line, these satellites occasionally assume triangular and other arrangements.

Looking at the planet through a telescope, you will first see a pair of dark stripes. These stripes – one above and one below the equator – are the North and South Equatorial Belts. Through larger telescopes and with higher magnifications, more dark belts and bright zones come into view.

Jupiter continues to be visible easily in the evening sky through October. Each evening between opposition and then, Jupiter appears slightly farther to the west. On November 21, Jupiter lines up with the Sun (a configuration called conjunction) and is invisible from our point of view.

Observers out admiring Jupiter may spot some shooting stars. These streaks of light are part of the Eta Aquarid meteor shower that peaks before dawn May 5.

Here are some quick facts about Jupiter:
• Jupiter is the solar system’s largest planet. Not only would 1,266 Earths fit inside Jupiter, but the eight other planets would comprise only 68.8 percent of Jupiter’s volume.
• Jupiter is 318 times as massive as Earth.
• On a moonless night at a dark site, Jupiter can cast a visible shadow.
• At its equator, Jupiter rotates at 27,900 mph, more than 27 times as fast as Earth.
• Jupiter spins so rapidly that it is flattened. Its polar diameter is only 93 percent of its equatorial diameter. Jupiter completes one rotation in less than 10 hours, allowing the entire planet to be viewed during a single night this month.
• Jupiter is the second most reflective planet (next to Venus). Jupiter reflects 52 percent of the sunlight falling on it.
• Jupiter moves roughly the width of the Full Moon across the sky in a little over 6 days.
• The brightest moon visible from Earth (not counting our Moon) is Ganymede, which shines at magnitude 4.4 when Jupiter lies at opposition. Io is next brightest at magnitude 4.7. Europa and Callisto rank third and fourth, respectively, at magnitudes 5.1 and 5.4.

For more information, please visit the following websites:

Space Explorers Mission: Solar System subscribers can also read more about Jupiter and the other planets by visiting our Space Library at www.space-explorers.com.

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