Transcript
Early Astronomy 22.1
Astronomy • The scientific study of the universe; it includes
the observation and interpretation of celestial bodies and phenomena.
Geocentric
• Describes the concept of an Earth—centered universe.
Heliocentric
• Describes the view that the sun is at the center of the solar system.
Retrograde Motion • The apparent westward motion of the planets
with respect to the stars.
Ellipse
• An oval.
Astronomical Unit (AU)
• Average distance from Earth to the sun; 1.5x10⁸ Kilometers.
Key Concept
• In the geocentric model, the moon, sun, and the known planets—Mercury, Venus, Mars, and Jupiter– orbit Earth.
Key Concept
• In the heliocentric model, Earth and the other planets orbit the sun.
Key Concept
• Copernicus concluded that Earth is a planet. He proposed a model of the solar system with the sun at the center.
Key Concept
• Brahe’s observations, especially of Mars, were far more precise than any made previously.
Key Concept
• Kepler discovered three laws of planetary motion.
Key Concept
• Galileo’s most important contributions were his descriptions of the behavior of moving objects.
Key Concept
• Although others had theorized the existence of such a force, Newton was the first to formulate and test the law of universal gravitation.
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