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Article updated: 9/27/2011 7:57 AM

Scientists are studying Jupiter's Great Red Spot

Io, one of Jupiterís four major moons, is seen in front of Jupiter.

Io, one of Jupiter's four major moons, is seen in front of Jupiter.


Courtesy of Adler Planetarium

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By Hope Babowice

You wanted to know

"How was Jupiter's red spot made and how big is the planet?" asked Jen Janik's third-graders at Big Hollow Elementary School in Ingleside.


Suggested reading

Suggested reading
The Fremont Public Library District in Mundelein suggests these titles on Jupiter and space:
• "Far-Out Guide to Jupiter", by Mary Kay Carlson
• "Destination Jupiter", by Giles Sparrow
• "Jupiter: The Largest Planet", by Daisy Allyn
• "Out And About At The Planetarium", by Theresa Jarosze Alberti
• "D.K. Encyclopedia of Space", by Heather Couper

Jupiter, the fifth planet from the sun, is the largest planet in our solar system. The gas planet takes more than 11 years to orbit the sun.

Jupiter has four moons -- Io, Europa, Callisto and Ganymede, with 60 more smaller moons orbiting at differing rates. Using a telescope, you can see some of its moons and the Great Red Spot (GRS), also called the Eye of Jupiter.

Scientists have been trying to figure out what that Great Red Spot is for a very long time.

"No one really knows for certain. The Great Red Spot was first described in 1831 and has been continuously tracked since about 1880," Adler Planetarium Director Geza Gyuk said. "It is certainly more than 150 years old and quite possibly hundreds of years old."

Spacecraft have been taking close-up pictures of the Great Red Spot and Jupiter's moons since the 1970s.

"Now that we have very high resolution images from space craft and the Hubble Space Telescope, we can tell the GRS is a huge storm not unlike a hurricane here on Earth," Gyuk said.

"Its longevity is probably due to the fact that it is so large, larger than Earth, and also because, unlike a hurricane here on Earth, there is never any land that it can move over to slow it down or make it stop."

Scientists answer these space puzzles using observation and by developing mathematical equations to test theories.

Whenever possible, they also collect samples. Jupiter had a visitor in 1995, an atmospheric probe that collected data for nearly an hour before it was crushed by atmospheric pressure that was 23 times stronger than the Earth's.

Jupiter is a stormy planet. The storms start out looking white and turn red as they grow larger.

"The storms may dredge up chemicals from deep within Jupiter. A particularly interesting example of this is the Red Spot Junior, which was formed from the merger of three white storms fairly recently. As it intensified, it turned red and is now about half the size of the GRS, which makes it about the size of the Earth, and has winds about as fast. It is possible that if the GRS continues to become smaller and the Red Spot Junior grows, then eventually the roles will be reversed."

So how big is Jupiter? If you take all the planets in our solar system and strap them together, Jupiter is 2.5 times larger than that, but still smaller than the sun. Jupiter is 88,846 miles across its equator. Compare that to Earth, which measures 8,000 miles across its middle.

Adler Planetarium members and students pay $5 to attend special lectures. On Thursday, Oct. 6, at 7 p.m., Jason Steffen, a team member of NASA's Kepler Mission and Fermilab astrophysicist, will talk about recent discoveries of planetary systems. NASA's Kepler Mission is using a space telescope to snap pictures in distant parts of the Milky Way.

For details, visit

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