first midterm notes

2 Pages
84 Views
Unlock Document

School
University of Toronto St. George
Department
Astronomy & Astrophysics
Course
AST101H1
Professor
Clifford Orwin
Semester
Fall

Description
Chapter 1 Our place in the Universe geocentric-ancestors thought we lived in an Earth-centered universe. Planet-large bodies which orbit stars,may be various mixture of rocky,gaseous,icy.1. Orbits stars directly,2 massive enough to be compress them into spherical shapes,3. Must have cleared their orbits. (Pluto is a dwarf planet cuz its orbit is full of objects like comets) Asteroid-rocky Comet-icy Moon- orbits a planet Nebula-a cloud of gas and dust, cud see light emitted by gas & parts where blocked by dust. Place where stars form. Stars form when parts of nebulae crushed by own gravity. Solar sys.-Earth is in it, and it consists of the Sun & objects that orbits it-planets, moons, countless small objects like rocky asteroids and icy comets. The sun is a star in the milky way. Galaxy-a great island of stars in space, containing fr. few hundred million to a trillion or more stars. Earth is at more than halfway from galactic center to the edge of the galactic disk. -some galaxies are isolated, some in groups. Milky way is one of the two largest among 40 galaxies in the local group.Its a huge disk shaped collection of 100 billion stars. -galaxy cluster-groups of galaxies w more than a few dozen members. -supercluster-region which galaxies g. clusters tightly packed. Our supercluster is called Virgo. Universe expanding-avg. Distance bw galaxies are increasing w time. The beginning of expansion is the big bang-14 billion yrs ago. But galaxies dont expand. Nuclear fusion-process which lightweight atomic nuclei smash tog.to make heavier nuclei.stars are born.gravity compress material in cloud ,the center becomes dense and hot to generate energy Early universe- only hydrogen& helium.Earth had more-CO2,O2,etc, from stars. We are star stuff. Light years-light fr. Star takes many yrs to reach us, so measure distance to stars in units called light year eg.Sirius,8 light yrs away, the appearance we see it today is actually how it looks 8 yrs ago. Observable universe-portion of entire universe that we can potentially observe.-14 billion light yrs. Voyage Scale-model solar sys.- sun as a grape fruit, jupiter as a marble, earth as ball point (pen). Earth is 15 m away. Solar sys. Is empty, so 300 football fields model. Universe is never static-Earth rotates on its axis once every 24 hrs-sol
More Less

Related notes for AST101H1

Log In


OR

Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.

Submit