It’s intrigued millions for centuries, worshiped by civilizations, calculated by scientists, walked by humans and the subject of hundreds of books, movies, songs and TV shows. It is the moon.
A remnant broken from Earth some four billion years ago, it orbits our planet every 27.3 days in synchronous rotation, meaning that the same side of the moon is always facing the Earth; hence the phrase ‘The dark side of the moon’, becoming even more popular after the Pink Floyd album of the same name.
Although called ‘Earth satellite’, the orbiting body has a circumference of 10,917.0 km and a diameter of 3,475 km. It weighs 73,476,730,924,573,500 million kg in units of mass, which is 0.0123 that of Earth.
The moon is 384,400 km or approximately 250,000 miles from earth. Scientists have named just about very part of the moon. Noting one of the more famous ones, the Sea of Tranquility. Also called Mare Tranquillitatis, where astronaut Neil Armstrong first landed his Lunar Module spacecraft with the words “Tranquility base here, the Eagle has landed”, then when he climbed down the later of the Eagle, the first man on the moon stated his famous words “That’s one small step for man, one giant leap for mankind”. (See Google’s map of the Apollo 11 landing locations)
Others noteworthy to mention here are Mare Imbrium / Sinus Iridium, which is the southern dark spot in the lower end of the picture.