ASTR 1150 Lecture Notes - Lecture 9: Spiral Galaxy, Royal Astronomical Society, Galactic Center
Document Summary
Astr 1150 - lecture nine: the milky way. All individually visible stars are in the milky way. Most stars appear in a diffuse band across the sky. William herschel made the first map of the galaxy in 1785 (counted stars in various directions relative to earth) Assisted herschel in his work and discovered comets. Won the royal astronomical society gold medal in 1828 (next woman to receive this medal would be in 1996- vera rubin who discovered dark matter) However, large clusters of stars (globular clusters) were found to be far beyond his original map. Most of galaxy is not visible from earth. Plane of stars that orbits galactic centre. Our sun is 30,000 ly from galactic centre. 70 ly above central plane of disk. Stars in the disk orbit the centre in the same direction. Named for the constellations they appear in. Our sun is in the orion (local) arm.
