How Saturn Cracked Open Enceladus's Icy Surface
Scientists have discovered how the four famed fissures on Saturn’s moon, Enceladus, formed.
The largest of the “tiger stripes” formed due to gravitational pressure exerted on the moon’s poles, according to a paper published December 9 in Nature Astronomy.
The other three fissures formed soon after, as pressure on nearby ice built up.
Since the Cassini first circled Saturn’s icy moon Enceladus, scientists have been captivated by its many mysteries. For instance, Enceladus has a thick icy shell, which caps a watery world below, and the moon spews jets of water vapor and organic compounds out into space.
But one of the moon’s most intriguing features is a series of fissures that splice through sections of its southern hemisphere. The "tiger stripes," as they’re often referred to, are a set of four cavernous fissures almost 85 miles long and roughly 21 miles apart.
“No other icy planets or moons have anything quite like them," planetary geophysicist Doug Hemingway of the Carnegie Institute of Science told Space.com.
For years, scientists weren’t sure how these tiger stripes formed, but now, a team of scientists from the University of California Berkley, the University of California, Davis, and the Carnegie Institute of Science have developed computer models that show Enceladus and Saturn's testy gravitational relationship.
Gravitational forces tug at Enceladus' equator as it orbits Saturn. Because of these forces, the moon’s poles are some of the warmest regions on its surface and have thinner ice than anywhere else on the moon, meaning they split open more easily.
The largest of the stripes, Baghdad Sulcus—named for the Iraqi capital—burst open first. Water spewed from the newly opened crack and rained back down along the fissure's edges. This extra weight put pressure on the nearby ice, causing a set of parallel rifts—named Cairo, Damascus, and Alexandria—to form.
Because of the unique gravitational pull Saturn exerts over Enceladus, there's a constant flow of fluids jetting out of the rifts, means they're unlikely to close anytime soon.
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