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Walk? Yes, that’s right. The Sea of Tranquility is not actually a sea, so Neil Armstrong didn’t have to walk on water. In fact, there isn’t a single sea on the lunar surface. The Sea of Tranquility is actually a lunar mare. Now, although the plural of ‘mare’, ‘maria’, is a Latin word that means ‘seas’, these maria don’t have water in them.
Lunar maria were named as such because early astronomers mistook these areas as seas. You see, when you look at the Moon, particularly its near side (well, we don’t actually get to see the far side), i.e., the side which practically constantly stares at us at night, you’ll notice certain features that are darker than others.
Compare the Moon to a grey-scale model of the Earth, and you’ll easily mistake those dark patches for seas. By the way, in case you’ve been reading article titles (not the entire article) on this site lately, you might recall us mentioning water on the Moon. There’s water alright … underneath the surface, so even assuming that they’re plentiful, they don’t qualify as seas.
Let’s go back to our main topic. Called Mare Tranquillitatis in Latin, the Sea of Tranquility is found in the Tranquillitatis basin of the Moon and is composed of basalt. Maria are seen from Earth as relatively dark because the lighter colored areas are much elevated than them and hence are better illuminated by light coming from the Sun.
Whenever color is processed and extracted from multiple photographs, the Sea of Tranquility gives off a slightly bluish shade. This is believed to be caused by the relatively higher metal content in the area.
The actual landing site of Apollo 11′s lunar module is now named Statio Tranquillitatis or Tranquility Base. To the north of that specific area you’ll find three small craters aptly named Aldrin, Collins, and Armstrong, the privileged crew of Apollo 11.
The lunar module of Apollo 11 was not the only spacecraft to have landed on the Sea of Tranquility. There was also the Ranger 8 spacecraft … although “crash landed” is a more appropriate term. It wasn’t a failed mission though, since it was really meant to impact the lunar surface after taking pictures throughout its flight before striking the Moon.
Some people actually think the Apollo missions, particularly the lunar landings, were part of an elaborate hoax. Click on this link to read what the Japanese SELENE Lunar Mission discovered.
NASA has a huge collection of reliable links related to the Apollo missions.
Episodes about the moon from Astronomy Cast. Lend us your ears!