On Fri, 20 Feb 2004 [EMAIL PROTECTED] wrote: > [EMAIL PROTECTED]: > > > Weeeellll, the Foucalt Pendulum would prove that the Earth rotates, but I > > don't think it gives any evidence that it revolves about the Sun. What > > could we do to take it a step further? > > > > It does in principle, but it would be hard to get the accuracy. Other > things, like parallax and astronomical aberration, are also impossible to > measure > with 15th-17th century technology. But I'm sure once you convinced people > with > a Foucault pendulum that the Earth moved *at all*, it would be only a small > step from accepting rotation to accepting revolution. > > Art Carlson > > P.S. I can't leave that loaded pun lying around where children might play > with it: The revolution was the rotation. Once that was accepted, the > revolution (of the Earth around the sun) was no longer a revolution (in world > view).
Clever! And quite possibly true, but I was hoping for something more concrete, rather than simply mind-opening. Thinking again about Foucalt's pendulum, I realize you're right: It makes a full turn (if situated at one of the poles) in a sidereal day, doesn't it? That would put it "off" a full day each (solar) year. What does happen at the equator, say? Simple geocentric mechanics would have the pendulum swing in an ideal straight line, if I recall. Does the annual motion introduce a small diurnal rotation, further reduced by the sine of the Earth's axial tilt? Accuracy in the mechanics of the pendulum would be overwhelming, but this *is* a thought experiment... Dave 37.277N 121.966W -
