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WORK CITED
Category. "Laws of Planetary Motion - Discover Johannes Kepler's Laws of Planetary Motion." Space & Astronomy at About.com. N.p., n.d. Web. 16 May 2011. <http://space.about.com/od/ast Discovery of Planet Mercury." Universe Today — Space and astronomy news. N.p., n.d. Web. 16 May 2011. http://www.universetoday.com/13957/discovery-of-planet-mercury/. "Newton." WSU Mathematics and Statistics. N.p., n.d. Web. 16 May 2011. http://www.math.twsu.edu/history/Men/newton.htm. -
WORK CITED
"The Solar System - Astronomy For Kids - KidsAstronomy.com." Astronomy For Kids - KidsAstronomy.com. N.p., n.d. Web. 16 May 2011. http://www.kidsastronomy.com/solar_system.htm. "Uranus l Uranus facts, pictures and information.." The Nine Planets Solar System Tour. N.p., n.d. Web. 16 May 2011. http://nineplanets.org/uranus.html. -
WORK CITED
"What Year was Mercury Discovered? - Answers.Ask.com." Ask Answers - Answers.Ask.com. N.p., n.d. Web. 16 May 2011. http://answers.ask.com/Science/Astronomy/what_year_was_mercury_discovered. "Who Discovered Mercury?." Universe Today — Space and astronomy news. N.p., n.d. Web. 16 May 2011. http://www.universetoday.com/38170/who-discovered-mercury/. -
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r, distance, and F is the gravitational force between them.. "Millennium Theory of Inertia and Gravity." Millennium Relativity. N.p., n.d. Web. 16 May 2011. <http://www.mrelativity.net/inert -
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"Planets - Zoom Astronomy." ENCHANTED LEARNING HOME PAGE. N.p., n.d. Web. 16 May 2011. http://www.enchantedlearning.com/subjects/astronomy/planets/. "The Outer Planets." Universe Today — Space and astronomy news. N.p., n.d. Web. 16 May 2011. http://www.universetoday.com/33292/the-outer-planets/. "The Outer Planets (The Gas Giants) - Bob the Alien's Tour of the Solar System ." Bob the Alien's Tour of the Solar System. N.p., n.d. Web. 16 May 2011. http://www.bobthealien.co.uk/outer.htm. -
Kepler published first two Planetary Motion Laws
In 1609 Kepler published his first two laws on Planetary Motion. The first law was "all planets move in elliptical orbits with the Sun at one focus and the other focus empty." The second law was "the line joining the planet to the Sun sweeps over equal areas in equal time interbals." -
Kepler published the third Planetary Motion Law
In 1619 Kepler published the third and final Planetary Motion Law. The law was "for any planet, the square of its period of revolution is directly proportional to the cube of its mean distance from the sun." -
Gravity and Inertia were discovered
In 1985 Newton discovered gravity. He saw an apple fall from a tree and the thought came to him. Gravity is one out of two things that keeps planets in their place. Galileo discovered inertia, but Newton was the one who found out that they went together. -
Mercury, Venus, Mars
Mercury, Venus, and Mars were all discovered in anciant times so there is no way to know exactly when they were discovered and by whom. All three of these planets are inner planets. Characteristics of these three planets are, they have a higher density than outer planets, smaller than outer planets , contains mainly rock and metal, has a solid surface. -
Jupiter and Saturn
Jupiter and Saturn were also discovered in anciant times. They are both outer planets. Charatereistics of these two planets are, they are large gas giants, they are much bigger than inner planets, mostly made of hydrogen and helium, each has its own system of moons. -
Uranus
Uranus was discovered on March 13, 1781 by William Herschel. Uranus is an outer planet. Characteristics of this planet are, it is a large gas giants, they are much bigger than inner planets, mostly made of hydrogen and helium, each has its own system of moons. -
Comets
A comet is a "dirty snowball" around the size of an Earth mountain. Usually very long and narrow ellipses. Produce tails of gas and dust when they approach the Sun. -
Meteoriods
A meteor is a chunk of rock, metal, or dust in space. -
Asteriods
The first asteroid was spotted in 1801 by Giuseppe Piazzi. Asteriods are small, rocky worlds. Most asteriods revolve around the Sun between Mars and Jupiter. -
Neptune
Neptune was dicovered in 1846 by James Challis and Johann Galle. Neptune's characteristics are, it is a large gas giants, they are much bigger than inner planets, mostly made of hydrogen and helium, each has its own system of moons. -
Pluto
Pluto was discovered in 1930 by accident. Pluto was classified as a dwarf planet because it is much smaller than all the other planets. Soon after Pluto was discovered, it was quickly determind that it wasn't an official planet due to its size.
