Moon and Saturn

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Moon and Saturn

Planetary scientists can hardly move these days without splashing into a new ocean — or at least a possible one. They’ve discovered that oceans of liquid water may be hidden below the icy crusts of many smaller bodies: several moons of the giant planets, the largest member of the asteroid belt, and even remote little Pluto.

One of the more recent “ocean worlds” may be Mimas, a moon of Saturn. It’s less than 250 miles in diameter. Its main feature is a giant impact crater. It’s so big that it makes Mimas look like a “death star” from Star Wars.

Mimas is pockmarked by a lot of craters. Many of them are so old that scientists had thought the little moon was dead, with nothing happening inside it. But precise measurements of Mimas’s orbit and its rotation on its axis revealed some odd “wobbles.”

Scientists proposed a liquid ocean as a possible explanation for those wobbles as early as 2014. A study released earlier this year solidified the case. It found that the ocean could lie 15 miles or so below the surface, and account for up to half of the moon’s volume. The ocean would have formed no more than 25 million years ago. That’s not enough time for evidence of it to show up on the surface. So the ocean remains hidden deep inside this “death-star” moon.

Look for Saturn especially close to our own moon in the wee hours of tomorrow morning. It looks like a bright star just above the Moon at dawn.

Script by Damond Benningfield

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