ASTR 3 Lecture Notes - Lecture 3: Tropical Year, Lunar Eclipse, The Moons
Document Summary
We think of the sky as a celestial sphere to understand the motions in the sky. Motion of celestial objects: sun rises from east, reach a height near noon, and sets in the west. The star do the same thing: east to west. Because the earth spins on its axis on a daily cycle. Convenient fiction: earth staying still while the sun and stars rotate around us. The center of the rotation of stars is the north celestial pole=polaris, it happens to sit very close to the northern celestial pole (extension of north pole). No star sits near the southern celestial pole. The location of the sun in the sky depends on where we observe: how far south/north from the equator we are. Different stars in different seasons of the year. Our (cid:28662)onst(cid:28664)ll(cid:28660)t(cid:28668)ons (cid:28663)(cid:28664)p(cid:28664)n(cid:28663) on t(cid:28667)(cid:28664) on(cid:28664) (cid:28661)(cid:28664)(cid:28667)(cid:28668)n(cid:28663) t(cid:28667)(cid:28664) sun (cid:28603)t(cid:28667)(cid:28664) on(cid:28664) w(cid:28664) (cid:28663)on"t s(cid:28664)(cid:28664)(cid:28604).
