The ice caps, first observed by Giovanni Cassini in 1666, immediately raised tantalizing questions. Are they made of water ice like the giant glaciers that smother Antarctica?

• 1666年，由乔万尼·卡西尼发现的冰冠立即引发了一些问题：它们也是由像包围着南极洲的巨大的冰川一样的冰水构成的吗?