10 Quick Facts about the Moon

10 Quick Facts about the Moon

Become an expert on the Moon in 5 minutes or less

1. It orbits the Earth at an average distance of 240.000 miles or 384.000 kilometers (or 0.0025 astronomical units).

The difference between its closest point (perigee) and its farthest point (apogee) is 25,000 miles (40,000 km). It also takes the Moon roughly 27 days to make a complete orbit around our planet.

2. There’s no such thing as a dark side of the Moon, but there is a far side of the Moon.

Far side of the Moon. Photo Credit: NASA Blueshift via Flickr

Far side of the Moon. Photo Credit: NASA Blueshift via Flickr

All sides receive sunlight. However, the Moon is tidally locked with our planet which means that the same side is always facing us.  So, when we look at it at night, we only ever see one side. The other one has only been seen from spacecrafts.

3. It’s full of trash.

This doesn’t mean that astronauts went there, had a picnic and forgot to pick up after themselves. Rather it has to do with the standard procedure of ending unmanned lunar missions – crashing the probes. There are over 70 various spacecrafts on the Moon, as well as a few flags, some golf balls, some TV cameras, empty packages and, worst of all, human waste containers – totaling over 400,000 pounds.

4. It’s drifting away from us.

Photo Credit: Bluedharma via Flickr

Photo Credit: Bluedharma via Flickr

The Moon used to be much closer to Earth – approximately 14,000 miles (22,500 kilometers). It’s drifting away at a rate of about 1.5 inches (4 centimeters) per year. It’s also about the same speed our fingernails grow. This also leads to the (currently) bizarre situation where the Moon and Sun appear roughly the same size in the sky. This happens because the Sun has 400 times the diameter of the Moon, but it is also 400 times farther away.

5. It’s not completely inactive.

When astronauts used seismometers on the Moon, they discovered minor geological activity in the form of moonquakes. They can even cause fractures in the surface of the Moon.

6. 12 people have walked on the Moon so far.

Lunar_Rover_and_Irwin Apollo 15

The first was Neil Armstrong during the Apollo 11 mission in 1969 and the last was Harrison Schmitt during the Apollo 17 mission in 1972. All of them have been American astronauts.

7. It’s full of craters.

The Moon’s surface has been pelted with asteroids and meteorites for billions of years. It still has all its scars because there is no rain or wind to cause erosion.

8. It’s not the largest satellite.

Photo Credit: Primefac via Wiki Commons

Photo Credit: Primefac via Wiki Commons

Our solar system has well over 100 satellites orbiting planets (most of them around Jupiter and Saturn). The Moon is the fifth largest. The biggest one is Ganymede orbiting Jupiter and after it it’s Saturn’s Titan.

9. It’s called just the Moon.

It can get a bit confusing to distinguish between our Moon and other moons referring to satellites of other planets. That is because we’ve known about the Moon ever since we looked up at the sky. However, it wasn’t until 1610 that Galileo discovered that other planets have moons, as well. He used his telescope to discover the four biggest moons of Jupiter: Europa, Ganymede, Io and Callisto.

10. It was (probably) formed after a giant collision.

Moon collision

At the moment, we cannot say with absolute certainty how the Moon was formed. Several theories are still prevalent, but the one which seems most likely is the Giant Impact Theory. It states that around 4.5 billion years ago, during the early stages of our solar system, a giant object roughly the size of Mars collided with our planet. The impact was strong enough to throw massive amounts of debris into orbit. Over time, the debris gathered itself into a sphere and formed the Moon.

 

 

Featured image courtesy of Randen Pederson via Flickr.

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