Class Notes (1,100,000)
CA (630,000)
UTSG (50,000)
AST (700)
AST101H1 (500)
Lecture

September 15


Department
Astronomy & Astrophysics
Course Code
AST101H1
Professor
Michael Reid

Page:
of 1
assignment #1 is posted on masteringastronomy.com
office hours. teaching prof will stick around after
R. 12-1 on Thursdays: AB129
S. Kelly - online office hours, on Portal
T. assignments due monday at 11:59 pm
our solar system is special. the ones we’ve found are really different. special feature: the
way our planets are spaced out. all the small planets crammed against the sun, that’s
unique. means it’s warm for us = life. other planets are spaced out a whole lot.
1AU = average distance from Earth to Sun
intuitive unit. Mars is 1.5 AU from sun, so, 1.5x the distance the earth is from the sun
t takes a light a few years to travel between stars
the distance between the sun and the center of the galaxy is 26,000 light years = it
takes light 26,000 years to reach us from the center of the galaxy
galactic bulge, at the center of it, supermassive black hole, billion times bigger than our
sun
milky way’s a pretty big galaxy
*light travels at a finite speed* = anywhere you look, you’re looking back in time, always