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Solar System
Ch. 25.1: Solar System
Question | Answer |
---|---|
Geocentric | Model of solar system with Earth in the center. The sun and planets orbit around Earth. |
Heliocentric | Model of the solar system with the sun in the center. Planets orbit around Earth. |
Ptolemy | Scientist credited for mapping out the movements of planets around Earth in the geocentric model of the solar system. |
Epicycle | The circular movement of planets as they orbit Earth in the geocentric model (Circles within circles). Used by Ptolemy to explain retrograde motion of planets. |
Retrograde motion | Apparent motion of a planet in a backwards motion when observed from Earth. Really caused by Earth 'by passing' the planet as we orbit sun. |
Gallileo | Observes moons of Jupiter and phases of Venus to prove Copernicus's helocentric model |
Copernicus | Puts forth heliocentric model of the solar system. |
Ellipse | Oval shaped (like orbits) |
Gravity | Force of attraction between objects. This force keeps planets from wandering off. |
Inertia | The force that keeps planets moving in their orbits. |
Ecliptical Plane | The slice of space that planets orbit the sun in. |
Astronomical Unit (A.U.) | A unit used to measure distances in the solar system; 1 AU is the average distance from Earth to the sun. |
Inner planets | Mercury, Venus, Earth, and Mars |
Outer planets | Jupiter, Saturn, Uranus, Neptune |
Asteroids | Space rocks that separate the inner and outer solar system. |
Comets | Rock and frozen water; The most distant objects in the solar system. |