by Rose Sicard on October 09, 2012 Comments (0)
The Moon is odd, right? No matter where we stand on earth we can never view the "far side" or what more artistic souls have decided to call the "dark side" of the Moon. Why is that? You may Google this and read about it, but it's a bit hard to wrap your head around this counter-intuitive notion.
If indeed the moon rotates around its own axis AND orbits the earth we certainly should be able to see the other side... Well, not quite. There is a strange gravitational phenomena called "tidal locking" that has -over a very long period of time- locked the moon to the earth. I'm not going to get into the actual process of locking, but what happens when a smaller heavenly body tidally locks to a larger one.
Here's how it works in layman's terms:
The moon rotates around itself one full 360 degrees in about 29.53 days and this is roughly about the same amount of time it takes for it to orbit our planet. Still doesn't make sense perhaps?
Totally understandable, because one assumes that if the moon rotates around itself at any rate, it must be turning its back to us at some point.
The reality is hard to grasp at first until you play a game yourself:
1. Put a chair in the middle of a room. (forget about the earth's rotation for a minute; it has no bearing on understanding the concept)
2. Stand about a meter, or 3 feet away from the chair while facing it.
3. Move (as in you're orbiting the chair while always facing the chair) in 45 degree increments and stay on an imaginary circumference line.
4. Stop when you are across exactly from the spot you have started and observe your position now.
5. Do you realize that even though now you have rotated 180 degrees and are now seeing the opposite side of the room from when you started, you are still facing the chair? This is pretty much what the moon does.
6. Continue, until you end up where you started, while paying attention to how your body rotates to face the chair as you move.
Note that you never end up turning your back to the chair, yet you have now made a complete rotation around your own axis, but you were also orbiting the chair at the same rate.
7. Once you get back to where you started, it should be clear how the moon manages to never show us its backside (the Moon never moons us).
I hope this was helpful to any students or curious minds alike. It took me a while to understand this myself, but when you do, you will love showing other peeps how this works!