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Exploratour - Does Europa have an Ocean?

This image shows the Earth and the moon, and the bulges produced on each side from the tides.
Click on image for full size

The reason that Europa is warm is because of tides. An example of what happens is shown in this drawing of the Earth and Moon. In this picture, the Earth is pulling on the Moon, and the Moon is pulling on the Earth with gravity. The Moon pulls more strongly on the side of the Earth facing the Moon than on the side facing away from the Moon. Because planets are not perfectly rigid, they change their shape when they are pulled this way.

In the case of Europa, the push-me, pull-me effect is caused by the pull of Jupiter on one side, and the other moons of Jupiter on the other side. (Europa is an inside moon). The volcanism of Jupiter's moon Io is caused by the very same effect.

If a body is very rigid or is not held together well, instead of getting pushed and pulled out of shape, the tidal forces can actually tear the body in half, as with comet Shoemaker-Levy 9.

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Learn about Earth and space science, and have fun while doing it! The games section of our online store includes a climate change card game and the Traveling Nitrogen game!

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Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

ExploraTour - Looking at the World in a Different Light

Even though the sleeping man is no longer on the bed, you can still see where he was lying down. The heat from his body warmed up the bed sheets which are now radiating infrared light toward your eyes....more

ExploraTour - Looking at the World in a Different Light

All warm objects (not just people) radiate in the infrared. Warmer objects give off more infrared radiation. Very hot objects radiate other types of light in addition to infrared. Click on the picture...more

ExploraTour - Looking at the World in a Different Light

Your eye is a wonderful detector of visible light. Different frequencies of light produce different sensations in the eye which we interpret as colors. Our eyes detect light by using light sensitive components...more

ExploraTour - Looking at the World in a Different Light

Imagine you found a pair of special glasses that not only gave you telescopic vision but gave you the ability to see all forms of radiant energy. The universe in visible light contains all the familiar...more

ExploraTour - Looking at the World in a Different Light

This is a volcano on the island of Miyake in Japan. It has erupted, sending hot lava and ash into the air, a total of ten times. The time after one eruption until the next occurred was about twenty years...more

ExploraTour - Looking at the World in a Different Light

This is a picture of a galaxy in visible light. A galaxy is a large number of stars, some like our sun, some bigger, some smaller and all moving together through space. This galaxy is called Centaurus...more

ExploraTour - Looking at the World in a Different Light

This is a plant in Gary, Indiana where power is made. We use power to run things like television sets, radios, lights, and microwave ovens. The picture looks very strange because it was taken in infrared....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