NATS 1745 Lecture Notes - Lecture 3: Star System, Celestial Equator, Tropical Year

• School: York University
• Department: Natural Science
• Course: NATS 1745
• Professor: Robin Metcalfe

Document Summary

As earth spins, the stars appear to rotate around the north and south celestial poles because: earth is spinning 2. Stars always rise in the east and set in the west. Polaris is the northern star that determines the north. The(cid:396)e"s (cid:374)o (cid:271)(cid:396)ight o(cid:271)je(cid:272)t (cid:894)sta(cid:396)(cid:895) at the southe(cid:396)(cid:374) (cid:272)elestial pole (cid:271)e(cid:272)ause the south does(cid:374)"t ha(cid:448)e a pole star unlike the north. A(cid:374) o(cid:271)se(cid:396)(cid:448)e(cid:396)"s latitude is gi(cid:448)e(cid:374) (cid:271)(cid:455) the altitude of the (cid:448)isi(cid:271)le (cid:272)elestial pole (cid:894)the highe(cid:396) the latitude, the higher the pole) On the northern hemisphere, when polaris has an altitude of 90 degrees, our latitude is 90 degrees pola(cid:396)is" altitude (cid:894)(cid:374)o(cid:396)th (cid:272)elestial pole(cid:895) = ou(cid:396) latitude o(cid:374) ea(cid:396)th. North celestial pole marked by polaris, south celestial pole marked by nearby objects or constellations. Polaris is a triple star system that orbit around each other rather than just one single star but only polaris a is visible to our eyes on earth.