Scientific breakthrough: What caused the extinction of the woolly rhinoceros ten thousand years ago from an area in Europe covering the coasts of the Arctic Ocean in the north to the coasts of the Mediterranean in the south? What caused the extinction of the mammoth while other ice age mammals like the musk ox just barely survived to present day.

A giant cloud half the size of the United States has been imaged on Saturn's moon Titan by the Cassini spacecraft. The cloud may be responsible for the material that fills the lakes discovered last year by Cassini's radar instrument.