# Shared Flashcard Set

## Details

Gravitation and the Solar System
Terms concerning the start of learning about space.
15
Physics
03/01/2010

Term
 Two major early events
Definition
 1.The stars seem to rotate in fixed circles.2.The "wanderers" moved erratically.
Term
 Plato
Definition
 Knowing that the circle was the shape of the gods he gave his students the task of using circles to describe the movements of the planets.
Term
 Eudoxus
Definition
 Proposed the planets followed transparent spheres. Some spheres contained planets others did not. Each sphere was then attached to the sphere outside it. Each sphere was tilted at a specific angle and the spheres rotated at certain speeds. 13 spheres= mercury
Term
 Appolonius and Hipparchus
Definition
 They used a model in which the planets moved in circles and the centers also moved in circles.
Term
 Ptolemy
Definition
 Developed a model that was earth-centered. All the planets orbit in "circle-on circle" orbits.
Term
Definition
 when planets appear to stop and reverse direction and then stop again and continue in the original direction. This was explained in Ptolemy's model.
Term
 Copernicus
Definition
 Realized the Earth itself rotated and that it orbited around the sun. Also believed that the outer celestial sphere of stars did not move.
Term
 Martin Luther
Definition
 A monk that branded Copernicus as a fool and a heretic.
Term
 Tycho Brahe
Definition
 Believed that the Sun rotated around the Earth and the planets rotated around the sun. Made very precise measurements and measuring tools but was a poor mathematician.
Term
 Heracleides
Definition
 Thought that the Earth rotated on its axis.
Term
 Aristarchus
Definition
 Thought the Earth moved around the Sun.
Term
 Johannes Kepler
Definition
 A student of Brahe who was a brilliant mathematician and used Brahe's data to develop the theory. Took the radius of the largest planet and fit it into an isometric solid and then put a sphere inside that which ended up being the radius of the next largest planet. However, there are more planets than isometric solids. But it didn't quite fit Brahe's data so he scraped it.
Term
 Kepler's three laws
Definition
 1.The planets orbit the sun in elliptical orbits with the sun at one focus.2.The line joining the sun and any planet sweeps out equal areas in equal time intervals.3.R^3/T^2=K
Term
 Isaac Newton
Definition
 Reasoned that something is pulling the moon inward and thus proved that gravity exists.
Term
 Newton's Universal Law of Gravitation
Definition
 Fg=Gm1m2/d^2
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