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Europa: Facts About Jupiter’s Icy Moon And Its Ocean

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Europa is one of the Galilean moons of Jupiter, along with Io, Ganymede and Callisto. Astronomer Galileo Galilei gets the credit for discovering these moons, among the largest in the solar system.

Europa is the smallest of the four but it is one of the more intriguing satellites.

The surface of Europa is frozen, covered with a layer of ice, but scientists think there is an ocean beneath the surface. The icy surface also makes the moon one of the most reflective in the solar system.

Water plumes were spotted jetting from the moon in 2013, although those observations have not been repeated.

Several spacecraft have done flybys of Europa (including Pioneers 10 and 11 and Voyagers 1 and 2 in the 1970s).

The Galileo spacecraft did a long-term mission at Jupiter and its moons between 1995 and 2003.

Both NASA and the European Space Agency plan missions to Europa and other moons in the 2030s.




Galileo Galilei discovered Europa on Jan. 8, 1610. It is possible that German astronomer Simon Marius (1573-1624) also discovered the moon at the same time.

However, he did not publish his observations, so it is Galileo who is most often credited with the discovery. For this reason, Europa and Jupiter’s other three largest moons are often called the Galilean moons.

Galileo, however, called the moons the Medicean planets in honor of the Medici family.

It is possible Galileo actually observed Europa a day earlier, on Jan. 7, 1610. However, because he was using a low-powered telescope, he couldn’t differentiate Europa from Io, another of Jupiter’s moons.

It wasn’t until later that Galileo realized they were two separate bodies.

The discovery not only had astronomical, but also religious implications. At the time, the Catholic Church supported the idea that everything orbited the Earth, an idea supported in ancient times by Aristotle and Ptolemy.

Galileo’s observations of Jupiter’s moons as well as noticing that Venus went through “phases” similar to our own moon gave compelling evidence that not everything revolved around the Earth.

As telescopic observations improved, however, a new view of the universe emerged.

The moons and the planets were not unchanging and perfect; for example, mountains seen on the moon showed that geological processes happened elsewhere. Also, all planets revolved around the sun.

Over time, moons around other planets were discovered and additional moons found around Jupiter.

Marius, the other “discoverer,” first proposed that the four moons be given their current names, from Greek mythology.

But it wasn’t until the 19th century that the moons were officially given the so-called Galilean names we know them by today.

All of Jupiter’s moons are named for the god’s lovers (or victims, depending on your point of view).

In Greek mythology, Europa was abducted by Zeus, who had taken the form of a spotless white bull to seduce her.

She decorated the “bull” with flowers and rode on its back to Crete. Once in Crete, Zeus then transformed back to his original form and seduced her.

Europa was the queen of Crete and bore Zeus many children.

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Pass it on: New Scientist

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