The world rotates on its axis. We all know this. The sun rises and sets, a misnomer perhaps as it is less poetic but more accurately “earth move”, shadows lengthen, constellations shift from horizon to horizon during the night. I think of this on a regular basis. I work at Griffith Observatory where at local noon I watch an image of the sun cross a metal meridian, see the golden light of sunset streak in through the Planetarium doors, hear the cheers of visitors as the Pendulum swing knocks down a peg. Exuberant cheers that echo through the marble halls. And each time I wonder, are people seeing proof of the earth rotating, or do they only see the movement of the pendulum, slightly hypnotized by its continual swing, and a peg knocked to the ground? By Newton’s laws of inertia the swing of the pendulum is released from the rotation of the earth allowing us to see that we are indeed moving. As we all move together as one, it’s one of the few ways that allow us to see our earthly motion (particularly when we are inside a building). To be reminded that we are a ball spinning rapidly though space, on our axis and around the sun. We are in constant motion, with our planet and within our bodies. Our hearts beating, our breath in and out, molecules that multiply or decay. Always in motion. It is a fact. Facts that receive no applause are when a patron’s ticket flutters to the ground. Gravity seems less exciting, posssibly because it is simply there. As is the chemistry of the continual exchange of oxygen to carbon dioxide as we exhale to cheer. Perhaps the acclaim the pendulum receives for doing what it must do comes from being present to witness. A peg falling because it has crossed the path of a large swinging object becomes an event. It fulfills a human need for completion. Or to mark time. Or, for a split second, be in the presence of scientific understanding. Or perhaps folks just like a sure bet.