NATS 1740 Lecture 23: 25th February 2019

• School: York University
• Department: Natural Science
• Course: NATS 1740
• Professor: Michael De Robertis, Alireza Rafiee

Document Summary

We see a band of stars in our sky (in the milky way galaxy), appear in out sky as a faint band of light. Milky way: because ancient people has story about the man throw milk on and paint the sky. Dusty gas clouds can catch out view because they absorb visible light. This is the interstellar medium that makes new star systems. Primary features: disk, bulge, halo, globular clusters. 100,000 light-years are the size of galaxy. If we fly up and look down the milky way: it looks like a disk, and we can see its spiral arms. Further you are from the gravity centre, the less force you feel. The closer the star to the centre, the slower it moves. Stars in the disk moves in almost in the same direction with a little up-and-down motion because the gravity of disk stars pulls them toward. Their orbits are elliptical, in the bulge and halo, they have random orientations.