We didn't collectively understand the Earth was a planet until Copernicus developed the heliocentric model of the Solar System. We still have a little trouble with that, . (supposed) inhabitants of the moon. Wouldn't that mean the moon is called Selene (but we just don't use that name for lack of necessity?) read more
The Earth and the Moon's barycentre, their common centre of mass, is located 1,700 km (1,100 mi) (about a quarter of Earth's radius) beneath Earth's surface. The Earth revolves around the Earth-Moon barycentre once a sidereal month, with 1/81 the speed of the Moon, or about 12.5 metres (41 ft) per second. read more
The name of Earth's moon is "The Moon". Some people call it "Luna", which is the Latin name for the Moon. read more