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Unformatted text preview: Celestial sphere-Position- it is rotating upon the same axis Motion- the sphere rotates east to west, while the earth rotates west to east Sidereal day- time it takes the stars to make one circuit through sky 23 hrs 56 mins Solar day- average time it takes the sun to move once through the sky 24 hours Meridian- imaginary half circle from horizon due south to zenith to horizon due north. Geocentric model- the theory that the earth was the center of the universe and that everything in our solar system revolved around it Heliocentric model- the current theory used where everything revolves around a stationary sun. Finally proven by Nicholas Copernicus Keplers laws 1. Planets revolve in an elliptical orbit, sun is focus of the ellipse 2 .as a planet moves in its orbits, it sweeps out an equal amount of area in an equal amount of time (planet travels faster when closer to sun) 3 .more distant planets orbit the sun at slower average speed obey a precise formula Seasons- occur because the of the earths 23.5 degree tilt. When the northern hemisphere is towards the sun that is summer when it is away that is winter Eclipses Lunar Eclipse- the earth is putting a shadow on the moon (earth is between sun and moon) Solar Eclipse- the moon is putting a shadow on the earth (moon is between sun and earth) Conditions 1.the phase of the moon must be full (lunar eclipse) and new (solar eclipse) 2. The new or full moon must occur during a node of the moons orbit, happens twice a year . New moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, third quarter, waxing gibbous, starts over Penumbra- partially blocks sun umbra- completely blocks sun (area directly behind earth) Total lunar eclipse- moon passes through umbra. Penumbral eclipse- moon passes through penumbra Features 1. patterns in motion-planetary orbits are nearly circular and lie...
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This note was uploaded on 04/04/2012 for the course ASTRO 138 taught by Professor Nicholascerrutti during the Spring '11 term at Washington State University .
- Spring '11