iapetus

If the outer layers of Iapetus froze solid at this time, some remnant of that shape might be preserved.

Whatever the truth, the range is remarkable and makes Iapetus look like a walnut in space.

EVEN a cursory glance at Saturn's moon Iapetus reveals it to be an oddball.

The subsatellite would have spiraled slowly away from Iapetus until Saturn grabbed it.

The other half of Iapetus is relatively bright but oddly covered with long and thin streaks of dark.

In the 17th century, the astronomer Giovanni Cassini noticed Iapetus had one dark side and one lighter side, but had no idea why.

The ring circles in the same direction as Phoebe, while Iapetus, the other rings and most of Saturn's other moons go the opposite way.

And its flattened shape implies that Iapetus once spun very quickly, completing a rotation in 16 hours.

A sub-satellite of the Saturnian moon would explain two of the most puzzling features of Iapetus.

Possibly solving a 300-year-old mystery, two recent studies suggest a likely mechanism behind Iapetus' two-faced nature.

Scientists think material from the outer ring moves inward and slams into Iapetus.

This mini-moon then started to fall back towards Iapetus, they argue.

The ingredients of Iapetus are also peculiar.

But not before its outward drift sapped rotational energy from Iapetus and slowed it down.

The discovery offers a possible solution to the mystery of the moon Iapetus.

Half of Iapetus is so dark that it can nearly disappear when viewed from Earth.