Class Notes (836,518)
Canada (509,851)
AST101H1 (417)
Michael Reid (157)
Lecture 3

Lecture 3 - Tour of the Solar System - September 17.docx

3 Pages
70 Views
Unlock Document

Department
Astronomy & Astrophysics
Course
AST101H1
Professor
Michael Reid
Semester
Fall

Description
September 17, 2013. Lecture 3 – Tour of the Solar System  Nearest large galaxy to Milky Way is Andromeda o 2.5 million ly away  Light travels at a finite speed o Things we see in the sky are not as we are seeing them, we see them as they were in the past o E.g., takes 8 minutes for light from the sun to reach Earth, so if we look at the sun we are looking at it 8 minutes in the past o No matter where you look, you are looking back in time o E.g., takes 3 billionths of a second for light to reach our eyes from a light bulb if we stand a meter away o Light we see from Andromeda is 2.5 million years old, some of the stars giving off that light could already be dead and gone o Light from distant galaxies can be billions of years old  Lookback time = how far into the past we are seeing based on how long the light takes to reach us  Stars: balls of plasma which produce energy by nuclear fusion o Plasma = hot hot gas, ionized  Planets: rocky, icy, or gassy, and they don’t produce much energy o Mainly solids and liquids o Planets orbit stars and only planets o In 2006, the International Astronomical Union (IAU) accepted a new definition of the term “planet”, adding one new criterion to the traditional definition:  1. Planets orbit stars directly (not other planets).  2. Planets must be massive enough for their own gravity to compress them into spherical shapes.  3. Planets must have cleared their orbits. That is, there can’t be a lot of other stuff orbiting the parent star in orbits very similar to the planet. o Pluto can’t be a planet because its orbit is full of other objects (mainly comets)  Eris (orbits mainly outside of Pluto) is another that goes through all those comets  Pluto is a dwarf planet  The IAU recognizes only five dwarf planets in our solar system when there are potentially thousands  Dwarf planet: meets the first two criteria for a planet, but not the third (hasn’t cleared its orbit)  Moon: any large body which orbits a planet  Asteroid: a chunk of ice and rock which is not big enough to crush itself into a sphere  Nebula: is cloud of gas (bright) and dust (dark); Greek for “cloud”  Solar system: consists of a star orbited by planets, comets, asteroids, moons, dust, etc. o The inner solar system: Mercury, Venus, Earth and Mars o The outer solar system: Jupiter, Saturn, Neptune, Uranus, lots of comets and dwarf planets o Terrestrial planets: small, rocky, thing or not atmosphere, few or no moons  Earth, Mercury, Venus, Mars o Jovian planets: large, liquid and gas, small rocky core (probabl
More Less

Related notes for AST101H1

Log In


OR

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