PX269 Galaxies Part 2: Our Galaxy, the Milky Way 2.1 Components and Structure PX269 Galaxies.
Chapter 16 and 17: Discovering Galaxies The Milky Way Galaxy.
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Transcript of Chapter 16 and 17: Discovering Galaxies The Milky Way Galaxy.
Chapter 16 and 17: Discovering Galaxies
The Milky Way Galaxy
Whenever life gets you down, Mrs. Brown,And things seem hard or tough,And people are stupid, obnoxious or daft,And you feel that you've had quite eno-o-o-o-o-ough...Just remember that you're standing on a planet that's evolvingAnd revolving at nine hundred miles an hour,That's orbiting at nineteen miles a second, so it's reckoned,A sun that is the source of all our power.The sun and you and me and all the stars that we can seeAre moving at a million miles a dayIn an outer spiral arm, at forty thousand miles an hour,Of the galaxy we call the "Milky Way".Our galaxy itself contains a hundred billion stars.It's a hundred thousand light years side to side.It bulges in the middle, sixteen thousand light years thick,But out by us, it's just three thousand light years wide.We're thirty thousand light years from galactic central point.We go 'round every two hundred million years,And our galaxy is only one of millions of billionsIn this amazing and expanding universe.
Galaxies seem to take one of four different appearances
SPIRALS
Galaxies seem to take one of four different appearances
BARRED SPIRALS
Edge on Spiral
Galaxies seem to take one of four different appearances
ELLIPTICALS
Type E0 Type E3 Type E6
Galaxies seem to take one of four different appearances
IRREGULAR
Galaxies that look like merger remnants
Galaxy Mergers
Mergers cause the shapes of galaxies to change over time.
E
CD
B
Galaxy Classification
A
F
Our View of the Milky Way Galaxy
Our Milky Way Galaxy?
90% of a Galaxy is Dark Matter!
Measuring the amount of Dark Matter in the Universe: Gravitational Lensing
Einstein’s General Theory of Relativity says that light from a distant object gets bent when it passes through a gravitational field of an intervening object.
Perfectly Aligned Slightly Misaligned
Gravitational lensing
Gravitational Lensing:Evidence for dark matter
The Birth and Life of GalaxiesView of the Early Universe with WMAP (2003)
Early Universe showed slight variations in density!
Are the density variations the seeds of galaxy formation??
Now the popular choice for galaxy formation!
Young Galaxies
• smaller
• bluer
• more irregular
• higher starforming rates
Galaxies as they appeared more than 10 billion years ago.
Galaxies are Grouped in Clusters
Now the popular choice for galaxy formation!
The Local Group
The Local Super Cluster
Large-Scale Structure in the Universe
Superclusters, walls,and voids dominate thelarge scale structureof the Universe