Unless you've been living under a lunar boulder, you know that Monday, July 20, marks the 40th anniversary of the first moon landing by astronauts. To celebrate this special occasion, let's ponder a few fabulous facts about our astral neighbor, courtesy of National Geographic:
* By measuring the ages of lunar rocks, we know that the moon is about 4.6 billion years old, or about the same age as earth.
* The diameter of the moon is 2,160 miles and its mass is about one 80th of the earth's mass.
* The rotation of the moon – the time it takes to spin once around on its own axis – takes the same amount of time as the moon takes to complete one orbit of the earth, about 27.3 days. This means the moon's rotation is synchronized in a way that causes the moon to show the same hemisphere, or "face," to the earth at all times. The other hemisphere always faces away from us.
* The moon orbits the earth at an average speed of 2,300 miles an hour.
* The airless lunar surface bakes in the sun at up to 243 degrees Fahrenheit for two weeks at a time (the lunar day lasts about a month). Then, for an equal period, the same spot is in the dark and cools to about -272 degrees Fahrenheit.
* The moon is covered in rocky rubble created by constant bombardment by meteoroids, asteroids and comets.
Amazing, huh? Now go out there and take a good, long look at that beautiful moon.