sunset from behind the wire

sunset from behind the wire

Friday, March 13, 2015

Ganymede Update

Science that is distinguishable from magic is insufficiently advanced.

Almost every sci-fi movie that features alien invasions have them here to steal water from Earth in a classic (nuke their ass and steal their gas) scenario. Somebody needs to get the word to Hollywood that Earth isn't the largest supply of liquid saline water in the Solar System.

And if Aliens started pumping water from Ganymede, would we care?



Observation of Aurorae on Ganymede. NASA's Hubble Space Telescope observed a pair of auroral belts encircling the Jovian moon Ganymede. The belts were observed in ultraviolet light by the Space Telescope Imaging Spectrograph and are colored blue in this illustration. They are overlaid on a visible-light image of Ganymede taken by NASA's Galileo orbiter. The locations of the glowing aurorae are determined by the moon's magnetic field, and therefore provide a probe of the moon's interior, where the magnetic field is generated. The amount of rocking of the magnetic field, caused by its interaction with Jupiter's own immense magnetosphere, provides evidence that the moon has a subsurface ocean of saline water. Credit: NASA, ESA, and J. Saur (University of Cologne, Germany)
NASA's Hubble Space Telescope has the best evidence yet for an underground saltwater ocean on Ganymede, Jupiter's largest moon. The subterranean ocean is thought to have more water than all the water on Earth's surface.

Ganymede is the largest moon in our solar system and the only moon with its own magnetic field. The magnetic field causes aurorae, which are ribbons of glowing, hot electrified gas, in regions circling the north and south poles of the moon. Because Ganymede is close to Jupiter, it is also embedded in Jupiter's magnetic field. When Jupiter's magnetic field changes, the aurorae on Ganymede also change, "rocking" back and forth.

By watching the rocking motion of the two aurorae, scientists were able to determine that a large amount of saltwater exists beneath Ganymede's crust, affecting its magnetic field.

If a saltwater ocean were present, Jupiter's magnetic field would create a secondary magnetic field in the ocean that would counter Jupiter's field. This "magnetic friction" would suppress the rocking of the aurorae. This ocean fights Jupiter's magnetic field so strongly that it reduces the rocking of the aurorae to 2 degrees, instead of 6 degrees if the ocean were not present.

Scientists estimate the ocean is 60 miles (100 kilometers) thick -- 10 times deeper than Earth's oceans -- and is buried under a 95-mile (150-kilometer) crust of mostly ice.


18 comments:

  1. Replies
    1. We live in an interesting place -- surrounded by other interesting places.

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    2. I prefer my interesting places to be someplace I can breathe.

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    3. After the murder of those police officers in Fergusson, MO, I'm thinking of holding a sign up that says, "I can't breathe."

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  2. Replies
    1. I know, but you have to find a way to get under 60 miles of ice to ride the gnarly waves - dude. The fact that there is liquid water means that once you get through the ice, it's 32 degrees or warmer. Best wear a wetsuit when surfing the long right or left slide in tube city.

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    2. Not a snowboarder or into cold-sports, but the wetsuit was invented by a NorCal surfer. Personally I prefer warmth, palm trees, and Mai-tais.

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    3. Ganymede is not for you.

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    4. Try Enceladus (next blog post) - balmy and warm under 100 miles of ice.

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  3. comment... (just trying to raise my average)

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    1. Actually... I'm a bit too busy holding it together here
      to worry about sci-fi, weirdowood, or Ganymede.

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    2. Your average is officially approving - and Ganymede will be there whether or not you care...for the next fifty million years until the sun goes nova and blows itself up.

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  4. There are an amazing number of things we don't understand, contrary to Hollyweird... :-)

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    1. You can mention that here because the Hollywood types don't visit this blog, but they're very offended at the notion that they (and their God, Barak) don't know EVERYTHING.

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    2. As an official Hollywood Type, I have to say that your sexist post about a "moon" was, at best, Islamophobic.

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    3. "Islamophobia" implies fear. Nothing could be further from the truth. They are yearning to meet God. I only advocate speeding up the process for the jihadis.

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  5. Water in all its forms is one of the most abundant compounds in the universe if not the most abundant. We shouldn't be surprised that we're finding it in so many places.

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    Replies
    1. I don't find it surprising but I think that it's intensely interesting.

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