Global Science: Final Exam: The Earth in Space

The Earth in Space

A) "As to our distance from the center of the galaxy, the best guess is that we are 26,000 to 28,000 light years from the center. The estimates vary due to uncertainty in the exact size of the galaxy and the time it takes the solar system to complete one orbit of our galaxy." The Milky Way has an equator called an equatorial symmetry plane, and it looks like a very big circle, which is where we are located and where our planets orbit. (1) “The Universe - 10²⁷cm: There may not be a "size" to the Universe; it may be infinite. But, a crude estimate of the scale of the Universe can be made from looking back to the "beginning". Astronomers believe that the Universe began with the Big Bang, some 10 - 20 billion years ago. So, the most distant objects that we can see are about 10 - 20 billion light-years (= 10²⁷ cm) away.” (2) The structure of the universe can be thought of as a giant ball. Being on the surface, you don’t realize that you are actually on a curved surface. But Einstein's theory of general relativity proved it to be true. (3)

(1) http://www.astrodigital.org/astronomy/solarsystemgalaxy.html

(2) http://casswww.ucsd.edu/archive/public/tutorial/scale.html

(3) http://superstringtheory.com/cosmo/cosmo2.html

Picture: http://upload.wikimedia.org/wikipedia/commons/thumb/8/89/236084main_MilkyWay-full-annotated.jpg/220px-236084main_MilkyWay-full-annotated.jpg

B) The Big Bang Theory made the universe 15 billion years ago. This explosion created all existing matter and energy at one time. No one knows what existed before the Big Bang or if anything ever did. (4) The Big Bang could be recognized as a explosion within itself since nothing else was there before. It sent all parts of the universe away from each other and set the path for an ever-changing universe. (5)

(4) http://www.umich.edu/~gs265/bigbang.htm

(5) http://ssscott.tripod.com/BigBang.html

Picture: http://ssscott.tripod.com/bang.jpg

C) Cosmic Microwave Background has been able to say that the universe is 13.73 billion years old to within 1%. (6) The Cosmic Microwave Background is the cool remains of the echo caused by the Big bang, scientists use antennas to see the temperature of the CMB and can tell how far away it is, and when it happened. (7)