Textbook Notes (362,880)
Canada (158,081)
Astronomy (194)
Chapter 19

Chapter 19 Summary Cosmic Perspective

2 Pages
Unlock Document

Western University
Astronomy 1021
Chris Racknor

CHAPTER NINETEEN Our Galaxy The inability of visible light to penetrate deeply through interstellar dust and gas concealed the true nature of our galaxy until recent times modern astronomical instruments reveal the Milky Way Galaxy to be a dynamic system of stars and gas that continually gives birth to new stars and planetary systems Stellar winds and explosions make interstellar space a violent place hot gas tears through the atomic hydrogen gas that fills much of the galactic disk leaving expanding bubbles and fast moving clouds in its wake all this violence might seem quite dangerous but it performs the great service of mixing new heavy elements into the gas of the Milky Way Although the elements from which we are made were forged in the stars we could not exist if stars were not organized into galaxies the Milky Way Galaxy acts as a giant recycling plant converting gas expelled from each generation of stars into the next generation and allowing some of the heavy elements to solidify into planets like our own What Our Galaxy Looks Like The Milky Way Galaxy is a spiral galaxy consisting of a thin disk about 100 000 light years in diameter with a central bulge and a spherical region called the halo that surrounds the entire disk the disk contains most of the gas and dust of the interstellar medium while the halo contains only a small amount of hot gas and virtually no cold gas How Stars Orbit in Our Galaxy Stars in the disk all orbit the galactic centre in about the same plane and in the same direction halo and bulge stars also orbit the centre of the galaxy but their orbits are randomly inclined to the disk of the galaxy orbital motions of stars allow us to determine the distribution of mass in our galaxy How Gas is Recycled in Our Galaxy Stars are born from the gravitational collapse of gas clumps in molecular clouds massive stars explode as supernovae when they die creating hot bubbles in the interstellar medium that contain the new elements made by these stars eventually this gas cools an
More Less

Related notes for Astronomy 1021

Log In


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


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.