- FILE/NASA

Learn about Jupiter, king of the planets

Date published: 7/5/2007

WHEN I HEAR the word "king," I don't think of a singer, fast food restaurants, or a cartoon television show. Instead, I think of Jupiter, the king of the planets.

With its massive size and its 63 known moons, Jupiter resembles a mini-solar system. It is the largest of the "gas giant" planets of the outer solar system. Like the sun, it's composed mainly of hydrogen and helium.

Astronomers estimate that if Jupiter had been about 80 times more massive, it might have become a star like the sun.

Jupiter's cloud-covered atmosphere is an ever-changing myriad of colors and features, which vary as the planet spins on its axis, approximately once every 10 hours.

July offers fine views of the planet in the southern sky a few hours after sunset during the warm Fredericksburg evenings .

Truly a showpiece, it is impressive in even the most modest optical instruments. A small backyard telescope will show its two main cloud belts, its famous Great Red Spot, and its four largest moons.

Jupiter takes about 12 Earth years to circle the sun. That means a year on Jupiter, the fifth planet from the sun, is equivalent to about 12 of our years.

Several manmade robotic spacecraft have studied Jupiter. Some of these spacecraft include Pioneer 10 and 11 in the early 1970s, Voyager 1 and 2 in the late 1970s, and Galileo in the 1990s. Jupiter was photographed earlier this year by the New Horizons spacecraft as it flew by the planet on its way to a rendezvous with Pluto in the year 2015.

These exploratory spacecraft have discovered intriguing things on and around Jupiter--deadly radiation belts, a ring around the planet, lightning bolts in the planet's atmosphere and active volcanoes on Io, one of its moons.

Io resembles a cosmic pizza with its lava-covered surface. See this link for a great photo of Io: http://apod.nasa.gov/apod/image/9703/io970321_gal_big.jpg

In July 1994, Jupiter became a cosmic crash scene when comet Shoemaker-Levy 9 struck the planet. Jupiter's gravity was so strong that it broke the comet into several pieces before the comet fragments crashed into the planet. This was the first time that astronomers witnessed a live collision between two objects in the solar system.

Date published: 7/5/2007