Exploration of the Moon invention of the telescope, an increasing number of people began to recognise the Moon as a sphere, though many believed that it was "perfectly smooth". In 1609, Galileo Galilei drew one of the first telescopic drawings of the Moon in his book and noted that it was not smooth but had mountains and craters. Later in the 17th century, Giovanni Battista Riccioli and Francesco Maria Grimaldi drew a map of the Moon and gave many craters the names they still have today. On maps, the dark parts of the Moon's surface were called "maria" (singular "mare") or seas, and the
Lunar craters a new lunar impact crater database similar to Wood and Andersson's, except hers will include all impact craters greater than or equal to five kilometers in diameter and is based on Clementine (spacecraft) images of the lunar surface. The "moon zoo" project within the Zooniverse program aimed to use citizen scientists to map the size and shape of as many craters as possible using data from the NASA Lunar Reconnaissance Orbiter. However, it has since been retired. Craters constitute 95% of all named lunar features. Usually they are named after deceased scientists and other explorers. This tradition comes from Giovanni