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A Global Ocean Has Been Discovered on One of Saturn’s Moons

Scientists have long known about the “ice geysers” that spray water vapor and ice particles near the south pole of Saturn’s moon Enceladus. New data from NASA’s Cassini mission shows that this activity is being fed by a vast global ocean beneath the moon’s icy surface.

Researchers studying Enceladus’ orbit around Saturn observed that the moon had a very slight wobble. This was an indication that the moon’s icy crust wasn’t frozen all that way through, and that a liquid water ocean was present between its surface and its rocky core.

It had previously been suspected that a regional sea brewed beneath the south pole of Saturn's geologically active moon. Gravity data collected during Cassini’s several close flybys supported the theory that the sea was in fact global, and this new analysis confirms that.

The Cassini-Huygens spacecraft has been orbiting Saturn since 2004. Enceladus has become of particular interest to the mission because of its potential to sustain life. Among the ice and vapor observed shooting from its southern volcanoes are complex, organic chemicals. The discovery of a liquid ocean further supports its astrobiological potential

It’s still unknown how Enceladus’ ocean keeps from freezing, but one possibility is that the tidal forces from Saturn’s gravitational pull generate much more heat than was once believed. The mission will extend through September 2017, and researchers will continue to sift through Cassini’s data for answers. On October 28, the spacecraft is scheduled to make a close fly by of Enceladus, coming within just 30 miles of its surface.

[h/t: Jet Propulsion Laboratory at NASA]

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History
The Queen of Code: Remembering Grace Hopper
By Lynn Gilbert, CC BY-SA 4.0, Wikimedia Commons

Grace Hopper was a computing pioneer. She coined the term "computer bug" after finding a moth stuck inside Harvard's Mark II computer in 1947 (which in turn led to the term "debug," meaning solving problems in computer code). She did the foundational work that led to the COBOL programming language, used in mission-critical computing systems for decades (including today). She worked in World War II using very early computers to help end the war. When she retired from the U.S. Navy at age 79, she was the oldest active-duty commissioned officer in the service. Hopper, who was born on this day in 1906, is a hero of computing and a brilliant role model, but not many people know her story.

In this short documentary from FiveThirtyEight, directed by Gillian Jacobs, we learned about Grace Hopper from several biographers, archival photographs, and footage of her speaking in her later years. If you've never heard of Grace Hopper, or you're even vaguely interested in the history of computing or women in computing, this is a must-watch:

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science
Why Are Glaciers Blue?
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The bright azure blue sported by many glaciers is one of nature's most stunning hues. But how does it happen, when the snow we see is usually white? As Joe Hanson of It's Okay to Be Smart explains in the video below, the snow and ice we see mostly looks white, cloudy, or clear because all of the visible light striking its surface is reflected back to us. But glaciers have a totally different structure—their many layers of tightly compressed snow means light has to travel much further, and is scattered many times throughout the depths. As the light bounces around, the light at the red and yellow end of the spectrum gets absorbed thanks to the vibrations of the water molecules inside the ice, leaving only blue and green light behind. For the details of exactly why that happens, check out Hanson's trip to Alaska's beautiful (and endangered) Mendenhall Glacier below.

[h/t The Kid Should See This]

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