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Europa

Page history last edited by PBworks 12 years ago

Europa

 


 

Planetary Data

 

Mean diameter3121.6 km0.245 Earths
Surface area3.1×107 km20.06 Earths
Volume1.593×1010 km30.015 Earths
Mass4.8×1022 kg0.008 Earths
Mean density3.014 g/cm3
Surface gravity1.314m/s20.134 g
Escape velocity2.025 km/s
Rotation period3.55118 d(synchronous)
Rotation velocity
Axial tilt
Albedo0.67
Surface* temp.min~50 K
mean103 K
max 125 K

 

Atmospheric Data

Avg Atmospheric pressure1 µPa
HeightTrace
Constituents
Oxygen100%

 

 

Geological Data

The Europan surface is relatively smooth; few features more than a few hundred meters high have been observed, but topographic relief in places approaches a kilometer (0.62 miles). Europa is the smoothest object in the solar system. The prominent markings crisscrossing the moon seem to be mainly albedo features, which emphasize low topography. There are very few craters on Europa, and its albedo is one of the highest of all moons. This would seem to indicate a young and active surface; based on estimates of the frequency of cometary bombardment that Europa probably endures, the surface is about 20 to 180 million years old 5 (the geological features of the surface clearly show a variety of ages).

 

It is thought that under the surface there is a layer of liquid water kept warm by tidally generated heat. The temperature on the surface of Europa averages about 110 K (-163 °C) at the equator and only 50 K (-223 °C) at the poles, and so the surface water ice is permanently frozen. The first hints of a subsurface ocean came from theoretical considerations of the tidal heating (a consequence of Europa's slightly eccentric orbit and orbital resonance with the other Galilean moons). Galileo imaging team members have analyzed Voyager and Galileo images of Europa to argue that Europa's geological features also demonstrate the existence of a subsurface ocean.

 

Spectrographic evidence suggests that the dark reddish streaks and features on Europa's surface may be rich in salts such as magnesium sulfate (Epsom salt), deposited by evaporating water that emerged from within. Sulfuric acid hydrate is another possible explanation for the contaminant observed spectroscopically. In either case, since these materials are colorless or white when pure, some other material must also be present to account for the reddish color. Sulfur compounds are suspected.

 

 

 

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