A quiz for you: why does the moon spin about its axis?
Does it really? I am now confused about that one. :-(
BTW, I’ve been sharing this thread with my son when he’s here and awake. He thanked me for posting it and we’ve been discussing it. Unfortunately, the visual similation he gave me was not much help. He used 2 of my jars of moisterizes with a flashlight being the sun. The smaller jar was the moon orbiting the sun. Thing is, the way he did it, the little jar didn’t turn on it’s axis. The name stayed facing the earth so that when it was on the back side of the earth it was getting some light from the sun (flashlight) and when it was between the earth and the sun (usually an eclipse, It hought) the other side got sunlight but the part (name side) facing the earth was dark.. It makes even less sense now. I should have stuck with my theory, which made more sense.
Here’s another image:
There’s a tree in a field. A hunter has chased a squirrel onto the trunk of that tree. The squirrel runs to the opposite side of the tree, looking up into the canopy, with his little belly facing the tree. Like this:
S T————- H
The hunter begins stalking the squirrel clockwise around the tree; the squirrel decides to follow him around, all the time keeping upright and all the time keeping his little belly facing the tree-trunk.
Let an arrow point the direction in which the squirrel’s belly faces, and let ‘O’ stand in for the squirrel. Like this - pardon the dots, which dont’ have a purpose in the diagram:
. . . . . O
. . . . . |
. . . . . v
O—> Tree <—O
. . . . . ^
. . . . . |
. . . . . O
The squirrel has gone around the tree, but has it turned on its on spine? Well, yes, if you compare the squirrel to the field: If O is the squirrel, and he started out on the S side of the tree-trunk, and he then went clockwise, his little belly would first face N, then E, S, W, and back to facing N. So the squirrel did rotate on his spine. That rotation took exactly as long as his ‘revolution’ around the tree-trunk.
Let the squirrel be the Moon, the tree-trunk the earth, and the hunter the Sun. YOu have the situation for saying the Moon rotates on its axis while keeping the same face always turned towards us.
Here’s another thing to try. Hold up a quarter at arm’s length and get George (Washington, not our George) to face you. just turn around like that in front of a bright window. George is always facing you, yet his face is pointing N, W, S, E and N again. That’s the coin ‘rotating’ on its axis in comparison with the room. And of course, George’s face is sometimes getting full Sun when your back is to the window, and is dark in it’s ‘new’ phase when you’re facing the window.