According to ptolemy's model of the movement of celestial bodies,
a. the earth rotates around the sun.
b. the sun is the center of the universe.
c. the earth rotates around the moon.
d. planets orbit in circular paths around the earth.

The arrival of in the early days of europa’s existence could have formed its ocean. it is likely that the water experienced similar to earth. it is also possible that this water is retained beneath europa’s surface and in its atmosphere due to europa’s . 1.) a. precipitation b. water vapor c. icy debris 2.) a. gravitational compression b. biochemical cycling c. radiogenic heating 3.) a, gravity b. magnetic field c. heat energy for plato