We can see this process as comets approach in the growing coma around the rocky core.

It has a small rocky core about the size of the Earth at its centre.

Deep within this shell is believed to be a small, rocky core about the size of Earth.

Picked up a lot of ice crystals over a rocky core.

They both contain massive rocky cores that are bigger than Earth.

Theoretical models allowed the possibility of a rocky core, but you can't get there.

At its centre, Titan has a rocky core that is about 3400 km thick.

It had a rocky core a dozen times as massive as the Earth.

Earlier it was assumed that Rhea had a rocky core in the center.

You have to go through over sixty-two thousand kilometers of hydrogen to get to the rocky core.