Download Astronomy – The Milky Way Galaxy

Astronomy – The Milky Way Galaxy
The ______________ _________ Galaxy
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Contains more than ______ billion stars
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Is one of the two largest among 40 galaxies in the ___________ ____________.
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Our Solar System is located a little more than _______________ from the galactic center
to the edge of the galactic disk.
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Only one of roughly ______ billion ______________ in the Observable Universe.
Galaxies
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Definition: a system that contains ______________ or ________ stars.
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_____________ _____________: groups of galaxies with more than a few dozen
members
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__________________: galaxies and galaxy clusters ___________ packed together.
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Classified using a diagram called “Hubble’s Tuning Fork”
Our Cosmic Address
1.
2.
3.
4.
5.
6.
Milky Way Galaxy Structure
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Known to look like ___________ pancake with a ___________ in the center.
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Named a _______________ Galaxy because of its _________ __________.
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Approximately ________________ light years away from the nuclear bulge.
Parts of the Milky Way Galaxy
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_______________ ______________: sphere of stars and other material at the heart of
our galaxy.
– about 4000 parsecs across (about a fifth of the total spread of the spiral arms of
the galaxy.)
– The very _____________ of our galaxy is a super-massive __________ _______.
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___-___ million times as massive as the sun.
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Appears to be powering a bright source of radio emission known as
Sagittarius A*.
Disk: _______, ____________ region of stars, dust and gas called ______________
___________ around the Nuclear Bulge.
– Can obstruct view for observations towards the Nuclear bulge.
– Approximately 1,000 light years in thickness and 100,000 light years across
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____________ ________: well defined ________ in the disk because of brilliantly
_________ stars.
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____________: ________________ in shape and contains little gas, dust, or star
formation.
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______________ _____________: a large _____________ spherical star cluster,
typically of _______ stars in the outer regions of a galaxy.
Formation of Galaxies
1. A Protogalactic cloud contains _____________ and ______________.
2. Halo stars begin to form as the protogalactic cloud starts to _______________.
3. Conservation of angular momentum ensures the remaining gas ___________ into a disk.
4. Billions of years later, the star-gas-star cycle supports ongoing _________
______________ within the disk. The lack of gas in the halo _______________ star
formation outside the disk.
Facts about Galaxies and the Universe
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Galaxies move ____________.
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Expansion began about _________ billion years ago (the ______ __________)
– This is called cosmological _______________.
– Proven by observing a faint glow of __________________ that is a remnant of
_________ from the Big Bang.
– Early Universe = __________ and ____________
– Today’s Universe = __________ and ________ ___________ because of
_________________.
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If you look at a galaxy that is 7 billion light years away you are seeing that galaxy as it
appeared 7 billion years ago.
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The number of stars in the observable universe is equal to the number of grains of dry
sand on all beaches on Earth.
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Large Magellanic Cloud and Small Magellanic Cloud orbit the Milky Way at 150,000 light
years and 200,000 light years.
Nearby Galaxies (Our Neighbors!)
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__________________ Galaxy is comparable in size, though slightly larger.
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Small galaxies (Sagittarius and _________ ____________ Dwarf Galaxies) are
____________ with us right now!
– These small collisions cause ____________ in our galaxy and create new
________ at points of _______________.
____________ _____________ (1889-1953)
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Studied ________ and ______________ outside the Milky Way galaxy.
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Designed a period-luminosity relation that proved that Andromeda is much too far
_______ to be part of Milky Way.
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Known for __________ _________
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The more ____________ the galaxy, the ___________ its moving away =
__________________ ___________________
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Galaxies are moving _________ in our _______________ universe.