Mike Shaw> I am rather disappointed to learn that there isn't an Mike Shaw> actual pole sticking out of the earth at the South pole to Mike Shaw> mark the spot. I wonder if there is one at the North pole? Mike Shaw> It would be really neat to drop an equatorial dial plate Mike Shaw> over it and create an instant sundial, even if it would Mike Shaw> only work for six month in each year - one at each pole Mike Shaw> needed! Who'll volunteer to make the expedition?
Mike Shaw> (I knew we would get back on topic eventually) Mike Shaw> Mike Mike Shaw> [EMAIL PROTECTED] Mike Shaw> 53.37N 3.02W The location of the pole (axis of rotation) changes. The following is extracted from an earlier email message I sent to this list: Jim Cobb> The earth's axis of rotation differs from its axis of figure Jim Cobb> (the maximum moment of inertia). The rotation axis moves Jim Cobb> slowly around the axis of figure in a quasi-circular path. Jim Cobb> The maximum amplitude of the polar motion is typically about Jim Cobb> 0.3 arc seconds (about 9 meters on the surface of the Jim Cobb> earth). This motion has principal periods of 365 and 428 Jim Cobb> days. Finally, the motion is affected by unpredictable Jim Cobb> geophysical forces and is determined from observations. Jim Cobb> Jim Cobb> I consulted "The Astronomical Almanac, 1999," page B 60 for Jim Cobb> most of the above information. "The Explanatory Supplement Jim Cobb> to the Astronomical Almanac" contains further information Jim Cobb> about polar motion, including a graph of about fifteen years Jim Cobb> worth of such motion. Jim ------------------- ---------------------- -------------------- | Jim Cobb | 540 Arapeen Dr. #100 | [EMAIL PROTECTED] | | Parametric | Salt Lake City, UT | (801)-588-4632 | | Technology Corp. | 84108-1202 | Fax (801)-588-4650 | ------------------- ---------------------- -------------------- Think like a man of action, act like a man of thought. -- Henri Bergson
