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The Question

(Submitted October 07, 1996)

What would alien life be like on Europa? I understand that the icy moon does have an atmosphere, though a very thin one, and that it contains oxygen obtained differently than on earth. Could this atmosphere support life? Could the dramatic temperature changes affect life (if there is) when Europa is blocked from the Sun because of Jupiter?

The Answer

As I am sure you already know, Europa is one of Jupiter's moons that Galileo discovered using a small (and very crude by modern standards) telescope.

Remember, there is one place in the solar system that we know life exists now -- Earth. So, you might want to think about comparing Europa to Earth as much as possible.

Europa's atmosphere does contain oxygen but it is extremely thin so it is hard to see how it could support life. However, Europa might have oceans under its icy crust. These would be kept liquid by heat from tidal friction. These hypothetical oceans would be more hospitable to life than the surface. Since they would be below a layer of ice and their main heat source would be tidal friction, having the Sun blocked by Jupiter wouldn't make much difference to them.

Some basic questions you should ask about Europa:

  • Is there an atmosphere? If so, what is it made of?
  • What is the surface gravity? (on Earth it is 1"g" = 9.8 m/s/s = 32 ft/s/s )
  • What is the temperature? How different is it from day to night?
  • How long are the days?
  • Does Jupiter block the Sun often?
  • Is there volcanic activity? If so, how does this affect it?
  • Are there more questions I should be asking?
Some basic questions you should ask about your creature:
  • Where does it get its energy? (We get ours from eating and breathing and then "burning" the food, to be very simplistic.)
  • How does it keep its body temperature about right? What is "about right" and why?
  • How does it move around -- or does it not have to? How does it reproduce?

For more information about Europa take a look at

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