Read Read Overview six: The milky way and other Galaxies. (this is between chapters 14 and 15. Do you have any questions? This overview gives a brief summary of some basics on Galaxies.
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How do we know the Milky way is flat and not a sphere?
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Read chapter 15:1 -15:3 Do you have any questions?
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watch this video on what will happen when andromeda collides with our galaxy: do you have any questions?
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There will probably be some stars that collide, but explain why the vast majority of stars will not collide with another star?
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He's talking a lot at the end about dark matter. from your reading what is your understanding of dark matter?
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Question 14
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If you clicked all of those, congrats! any of those might be PART of the problem. But when I said the numbers are off, i meant they are WAY off. so while we have have some things wrong about gravity distances and orbits, we think the majority of the wrong is in the mass. We think there is a lot of mass out there we just can't see. What mass have we already studied that we have a hard time seeing?
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Last video: its a little deeper into "what is dark matter"
do you have any questions?
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Which of the following are the three shapes of galaxies
planetary model
spiral
elliptical
bohrs model
irregular
spherical
spiked
Match the mystery to the theory that we have no visual proof for
What causes the different shapes of the galaxies?
Dark matter surrounds the galaxy
Stars are moving fast enough that they should be flung off into space. Gravity is holding it in, but there seems to be more gravity than we can account for with what we see.
super-massive black holes
strange light and ejected hot gas at the center of galaxies
different amounts of internal energy of a galaxy
Have you ever seen the Milky way, (on a trip, camping, somewhere away from city lights?)
yes
no
We learned that nebulae are fairly big, and more than one star is usually born out of the same nebula at the same time. That is one way we can figure out the age of stars. because all stars in the same star cluster are assumed to be more or less the same age.
True
False
What is a galaxy cluster?
A large group of stars within a single galaxy
A collection of hundreds to thousands of galaxies bound together by gravity
A region of space where new galaxies are forming from cosmic dust
The central core of a spiral galaxy, containing its oldest stars
remember all the way back to session 1 - we talked about orbits and gravity. We have equations that explain how fast a planet should move around a sun given what information about the star and the planet?
mass
volume
charge
density
Long story short: We can see a whole lot of stuff, and we can guestimate its mass. we can also guestimate distances and how fast stuff is orbiting other stuff and at the end of the day. and none of the number work. All that stuff works in a solar system, why doesn't it work at the scale of a galaxy. So why don't the numbers work
We are wrong about how gravity works at large scales
We are wrong about the mass
We were wrong about the distances
We were wrong about the orbits
What is a galaxy
What is a galaxy cluster
What are the different shapes galaxies come in
What is keeping galaxies together
Why galaxies spinning as fast as they do lead scientists to hypothesize dark matter