Exploratour - The Surface of Europa
The lack of craters on Europa told scientists that they had misjudged the age of Europa's surface. Moreover, as they examined each new picture, the age of Europa's surface seemed to get younger and younger. First scientists thought it was 3 billions years old, then they guessed it was only 1 million years old, then 10,000 years old, and finally they guessed that it might be currently active!
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