The Earth In Space



Earth.



 a) Our solar system is located in the outer edge of the Milky Way Galaxy. While orbiting, we are traveling about 155 miles per second. (1) It has been 13.75 gigayears since the "Big Bang" happened. Our universe is possibly infinite in size, but the region visible from Earth is approximately 46 billion light years. Our nearest sister galaxy is about 2.5 million light years away. The overall density of the universe that we have recently discovered is very low, about 9.9x10^-30 grams per cubic centimeter. (2) The universe has not been the same throughout its whole history though, research shows that it seems to have expanded. Even though there are many things in space and in our universe, the universe does NOT seem to have a net electric charge, nor net momentum and angular momentum.
 

Galactic North East of Solar System.






b) "According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in its present continuously expanding state." (2)







In 1912, Vesto Slipher

made the first

measurement of Doppler

shift- he

measured that of a spiral

nebula. He discovered that

almost all nebulae alike 

were receding from Earth. This and other research shows that the universe is 

expanding, supporting the Big Bang theory.  

c) Observing the Cosmic Microwave Background has

helped us determine the age of the universe because

CMB is radiation left over from an early stage in the

development of the universe. In the beginning of the universe, it was in full

thermal equilibrium. This means that photons were continually being emitted and absorbed, and everything was perfect. As the universe got bigger, it cooled to where photons could not be created, nor destroyed.  (2)

"In 1964, Arno Penzias and Robert Wilson accidentally discovered the cosmic background radiation while conducting diagnostic observations using a new microwave receiver owned by Bell Laboratories. Their discovery provided substantial confirmation of the general CMB predictions—the radiation was found to be isotropic and consistent with a blackbody spectrum of about 3 K—and it pitched the balance of opinion in favor of the Big Bang hypothesis."






1) "The Milky Way Galaxy - Zoom Astronomy." ENCHANTED LEARNING HOME PAGE. N.p., n.d. Web. 21 Nov. 2011. <http://www.enchantedlearning.com/subjects/astronomy/solarsystem/where.shtml


2) "Universe - Wikipedia, the free encyclopedia." Wikipedia, the free encyclopedia. N.p., n.d. Web. 21 Nov. 2011. <http://en.wikipedia.org/wiki/Universe#Size.2C_age.2C_contents.2C_structure.2C_and_laws