This preview shows page 1. Sign up to view the full content.
Unformatted text preview: Motion of the Sun I've put together two little movies that show how the changing orientation of the Earth's poles changes the coordinates. The first movie shows how the location of the celestial pole changes over time, from about 5000 BC to about 10,000 AD. The celestial pole would be at the center of the circle for the coordinate grid. This movie only shows part of the entire precession cycle (about half), but it is still enough to see how the "North Star" changes over time. We're actually kind of lucky to have the current star at that location now, since for most of the time there isn't a very bright star near the north Celestial pole. The second movie shows the effect of the changing alignment on the declination and Right Ascension system. The program is set up to show where the Sun is on the first day of spring - which is how we set the Right Ascension value, since that is where it equals 0, and on this date the Sun's declination is also 0. The program causes the grid to tilt a bit, but you'll see that the Sun remains on the 0 RA and 0 Dec location for each time step,...
View Full Document
This note was uploaded on 12/15/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.
- Fall '10