AS101 Study Guide - Final Guide: Top
Document Summary
Lesson 1: our time and place in the starlit universe. Precession: the earth"s rotational axis is pointed toward polaris, a star we traditionally call the north star, but this wasn"t always so. It begins with a picture of the earth tipped on its axis (it should show 23. 4 ) with the. North pole marked (np) (nep is the north equatorial pole don"t worry about that). Next the earth"s equatorial plane is shown as a green circle and we see the earth"s spin precessing slowly rotating in space. Of course, all the while earth is spinning on its axis, which they don"t show, but you can just imagine it. Next they show the background of stars and you begin to visualize the earth"s spin axis pointing to different areas in the northern sky (right now it"s within 0. 5 of polaris). Over the 26,000 year cycle it will point to other stars.
