Posted on August 28, 2021
This is an update of my post published on. August 28, 2010:
When Sir William Herschel first spotted Saturn's moon Enceladus, on this date in 1789, he didn't know it was special. It just looked like a little speck of light circling the magnificently ringed planet.
But we now know better. We had a spacecraft way out there near Saturn, Cassini, for almost two decades. It circled Saturn, taking measurements and photos, for 20 years. And what it showed about Enceladus is that half of the moon is cratered (like most planets and moons in the solar system) but the other half is smoooooth. Even more interesting, there are “tiger stripes,” which are four depressions or cracks, on one portion of the smooth half (shown here with false color), and water geysers periodically go off through cracks. The water instantly turns into ice, of course, and it is the apparently the snow made from these geysers that fills in and covers the craters and makes that part of the moon smooth.
That's pretty surprising, and nobody knows why the cracks and geysers are only on one part of the moon instead of scattered pretty evenly over the moon.
Recently, complex organic molecules - the ingredients for life! - were discovered coming up in those geysers. Hopefully we can get another spacecraft way out there to detect if there is life in the depths of the moon.
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Enceladus is in the thickest part of the sparse "E ring." It's only the sixth largest of Saturn's moons, only about 314 miles (or 505 km) in diameter. I read that it could fit inside the borders of Arizona! |
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