The major features of the Moon's surface can be seen by just looking up at it. It has lighter and darker areas. These distinctive terrains are the bright lunar highlands (also known as the lunar terrae, which is Latin for land) and the darker plains called the lunar maria, Latin for seas, which they resembled to Thomas Hariot and Galileo Galilei, the first scientists to examine the Moon with telescopes. The names terrae and maria were given to lunar terrains by Hariot and Galileo's contemporary, Johannes Kepler. In fact, the idea that the highlands and maria correspond to lands and seas appears to have been popular among ancient Greeks long before telescopes were invented. Although we now know they are not seas, we still use the term maria, and its singular form, mare.