The Galilean satellite Io floats above the cloudtops of Jupiter in this image captured by NASA's Cassini orbiter on the dawn of the new millennium, January 1, 2001.

The Galilean satellite Io floats above the cloudtops of Jupiter in this image captured on the dawn of the new millennium, January 1, 2001 10:00 UTC (spacecraft time), two days after Cassini's closest approach. The image is deceiving: there are 350,000 kilometers -- roughly 2.5 Jupiters -- between Io and Jupiter's clouds. Io is the size of our Moon, and Jupiter is very big.

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