Astronomy Outline

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Basics of Astronomy Outline

Complete the outline following the instructions above. Use the example as a guide, using complete sentences for all subpoints.

1. Our place in the universe
a. The modern view of the universe
1) What is our Sun and what is its role in the solar system? a) The sun is the closest star to earth and makes up 98% of the solar system mass. b) The sun is made up of the hydrogen, helium, calcium, sodium, magnesium, and iron elements. c) The sun provides light, heat, and energy to the Earth.

2) What is our Milky Way galaxy and the sun’s position in it? a) The Milky Way is an island of hundreds of billions of stars, gas, and dust held together by gravity to form a disk that is surrounded by a halo of globular clusters, which are smaller spherical groups of stars. b) The sun is about 26,000 light-years from the center of the Milky Way Galaxy. 3) What is the Big Bang and what does it say about the age of the universe? a) The Big Bang is based off of telescopic observations of distant galaxies that are expanding with time. b) By considering the rate of expansion, going backward provides an idea of initialization. By observed rate of expansion it is estimated to have occurred about 14 billion years ago. 4) What is meant by the phase “looking out in the universe is looking back in time?” a) This phrase is meant to describe the time it takes time for light from distant objects to reach the Earth. We see the sun as it looked about 8 minutes ago, other stars as they looked years ago, and distant galaxies as they looked millions or even billions of years ago. b. Where are we in the universe?

1) What is Earth’s place in the solar system?
a) Earth is the third planet from the Sun.
2) How close are the nearest stars to the Sun as compared to the distance between the Sun and the Earth? a) The sun is approximately 8 light minutes away from Earth. b) The second nearest star is Proxima Centauri and 4.24 light years away. c) Coming in at a close third is Alpha Centauri which has been considered as a double star and is 4.36 light years away.

3) How large is our Milky Way galaxy?
a) The disk of the Milky Way galaxy spans a distance of about 100,000 light years (one light year is about 9.5 x 1015 meters). 4) How many stars are estimated to exist in our galaxy?
a) Our Galaxy contains about 200 billion stars. Most of the stars are located in the disk of our galaxy, which is the site of most of the star formation because it contains lots of gas and dust. 5) How old is the earth compared to the universe itself?

a) A recent study puts the age of the Milky Way at approximately 14.5 billion years, plus or minus more than 2 billion years. b) The Earth is approximated to be about 4.54 billion years old. c. Motion in the universe

1) How fast does the Earth move around the Sun? Compare that to fast things in day-to-day life. a) The average distance from the Earth to the Sun is approximately 92,955,819 mi. Therefore in one year the Earth travels this distance and the velocity based on days and hours reveals approximately 18.5 miles per second b) The muzzle loading velocity of a M16 machine gun only amounts to approximately .61 miles per second. 2) How is our Sun moving in the galaxy?

a) It orbits the galactic center at a distance of roughly 27,000 light years, and it also oscillates through the galactic plane on a scale of tens of millions of years. 3) How are the galaxies around the Milky Way galaxy moving from our point of view? a) The Earth sits inside an arm of stars which are always going to be in front of our view of other galaxies far beyond the stars of our own galaxy. b) The galaxies are getting farther apart (on very large distance scales), with the velocity of recession proportional to the distance between them. 2. The sky and the science of astronomy

a. Explain the significance of the celestial sphere.
1) What important directions and coordinate systems help...
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