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Learn about planets outside our solar system through Exoplanets and Alien Solar Systems by Tahir Yaqoob, Ph.D., a book in our online store book collection.
This picture shows images of the Galilean Satellites taken by the Galileo spacecraft, as well as details from the surfaces of these moons.
Click on image for full size

Galilean Satellites

The Galilean satellites are the 4 big moons of Jupiter, Io, Europa, Ganymede, and Callisto. These moons are called Galilean because they were discovered by Galileo Galilei in 1610.

In this picture, Io, and Ioís surface, are shown on the left-most end, then Europa, and its surface, then Ganymede, then Callisto. Of Jupiterís 60 moons, these four are the biggest.
Last modified September 18, 2003 by Roberta Johnson.

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Europa was first discovered by Galileo in 1610, making it one of the Galilean Satellites. It is Jupiter's 4th largest moon, 670,900 km ( miles) from Jupiter. Europa's diameter is about half the distance...more


Callisto was first discovered by Galileo in 1610. It is the 2nd largest moon in the solar system, and is larger than the Earth's moon. It is about as big as the distance across the United States. Callisto...more


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The SAR Arc

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This figure shows the effect of the aurora on the atmosphere. When FAC's enter the atmosphere and create the aurora, they heat the atmosphere suddenly and abruptly. This creates an impulse which travels...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF