Friday, January 25, 2013

Chapter 1.3 Notes


Chapter 1.3 notes

·        -How is earth moving in our solar system?
Contrary to our perception, we are not “sitting still”
We are moving with the earth in several ways, and at surprisingly fast speeds.
·        -Earth orbits the sun once a year….
At an average distance of 1 AU= 150 million km
With earth’s axis tilted by 23.5 degrees.
And rotates in the same direction it orbits, counter-clockwise as viewed from above the North Pole.
·        -Our sun moves randomly relative to the other stars in the local solar neighborhood….
At typical relative speeds of more than 70,000 km/hr
But stars are so far away that we cannot easily notice their motion and it orbits the glaxy every 230 millions years.
·        -More detailed study of the Milky Way’s rotation reveals on of the greatest mysteries in astronomy.
·        -Most of milky way’s light comes from disk and bulge but most of the mass is halo.
·        -How do galaxies move within the universe?
Galaxies are carried along with the expansion of the universe.
·        -Hubble discovered that…..
All galaxies outside our local group are moving away from us.
The more distant the galaxy, the faster it is racing away
Conclusion: we live in an expanding universe
·        -We are never standing still.

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