Europa: Jupiter's Hoth

I recently wrote about Saturn's moon Titan, and how earth-like it appeared to be (at least in comparison to the other planets and moons in the solar system).  However, though the lakes of Titan may give it a somewhat earth-like appearances, it's lakes are not made up of water, but hydrocarbons like methane.  Jupiter's moon Europa, on the other hand, looks more like the 6th planet of the Hoth System (or just "Hoth" for short) from The Empire Strikes Back.

But despite Titan having arguably a slightly more earth-like appearance, the reality is, Europa may actually be more earth-like.  The big difference?  Europa has water...and a lot of it.  It may actually have even more water on it than Earth does.  That's quite a lot considering Europa is smaller than Earth.

Although Europa is also just slightly smaller than our own moon, it's actually the 15th largest object in our solar system.   It's even larger than Pluto.

But what about all that water?  According to NASA, Europa is completely covered in a salt water ocean that is perpetually frozen on the surface because it is so far from the Sun.  They think "tidal heating" causes Europa to be warmer than it otherwise normally would be at the distance it is from the Sun, which opens up the possibility that earth-like organisms could live deep within the ocean of Europa (see an article about the possibility of life on Europa here).

Here are a few more interesting bits of information about Europa:

-Judging from photos taken from the Gallileo spacecraft, scientists believe Europa is made of silicate rock.  They also believe it has an iron core and rocky mantle, much like Earth does.

-The surface of Europa is covered with cracks.  The cracks are thought to be the result of tidal forces beneath the surface caused by Europa's eccentric orbit (oval instead of circular) around Jupiter.  When Europa's orbit comes close to Jupiter, it's possible the tide of the sea may rise higher than normal.  If so, then the constant raising and lowering of the sea may be the cause of the cracks.  It's also believed that the ocean beneath the surface sometimes erupts through the surface and then freezes.

-Europa has a tenuous oxygen atmosphere.

Link for more information.

The European Space Agency (ESA) has already planned to send a probe to Jupiter to study Europa as well as two of Jupiter's other moons, Callisto and Ganymede.  It is suspected that Ganymede and Callisto may also have subsurface oceans.  It would be built in time for a 2022 launch, but it would take  the probe around 8 years to get to Jupiter, so it might be a while before we can glean much more information about Europa and its companions Callisto and Ganymede.