Worlds Beyond The Solar System

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Worlds Beyond The Solar System Anisa Noor October 21st 2014 SES4U Mr. Humpartzoomian Worlds Beyond The Solar System When we think of planets we do not often consider planets outside the friendly neighborhood of our Solar System. Our universe is constantly expanding with billions of galaxies inside of it, and to think all these galaxies hold nothing but stars is preposterous. If the planets in the Milky Way revolve around the Sun, there must be other celestial bodies revolving around stars elsewhere in space. Extrasolar planets, commonly called exoplanets, are planets that orbit stars outside the Solar System, but what makes such exoplanets actual planets and not just free-floating objects moving through space? These celestial bodies must follow three requirements to be classified as planets, stated by the International Astronomical Union (IAU) regarding the solar system, a planet must: orbit a star, have enough mass so that the star’s gravity pulls it into an elliptical orbit, and it must be gravitationally dominant, so that no other bodies of similar size hold a gravitational influence besides the planet’s own satellites. Now having known of exoplanets, what are they? How many are there? Say approximately one star holds one exoplanet in its orbit, then multiply this by 300 billion stars per galaxy, and then multiply this by the amount of galaxies in our universe; this is the expanse of the exoplanets we are dealing with. The first discovery of a planet outside the
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