한쪽으로 늘어진 위성

과학동아 1988년 11호

perhaps) and reflects considerable light. Some of it is dark (rocky, perhaps) and reflects little light. The planet Pluto, for instance, dims and brightens every 6.4 days. This represents its time of rotation, as it turns brighter and darker areas toward us.Then, too, the planet Saturn has a satellite named Iapetus that shows an even greater variation in light intensity than Nereid does. ...