This cloud turns Iapetus's entire leading hemisphere dark, keeping it warmer and ice - free. (scientificamerican.com)
The spectra showed that even Europa's leading hemisphere contains significant amounts of nonwater ice. (keckobservatory.org)
It covers the moon's leading hemisphere — the side that faces forward as it moves in its orbit — which suggests that the black material has been swept up from space as the moon moves around Saturn. (newscientist.com)