I teach about the Earth and Moon in my astronomy course, and compare the
two surfaces. I believe the Earth has about 600 active volcanoes, while
the Moon has none. Earth has about 175 major impact craters, while the
Moon has...?
I searched online for the number of lunar craters at least 1 km across,
and found a wide range of "estimates" (up to one million). Wikipedia lists
major craters alphabetically, but there are too many for me to count. Does
anyone know of a reliable study of lunar craters, or is it essentially
impossibly to get an accurate number?