astro final guide - Celestial sphere-Position- it is...

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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 nearly on the same plane- planets orbit the sun in the same direction-most planets orbit in the same direction and they orbit with a small axis tilt-most of the solar systems large moons exhibit similar behavior as the planets 2. existence of types of planets- terrestrial (earth like) mercury, Venus, earth, mars Small size and mass, high density, made mostly of rocks and metal, few if any moons, no rings, close to sun - Jovian (Jupiter-like) Jupiter, Saturn, Uranus, Neptune, Large size and mass, low density, made mostly of hydrogen helium and other compounds, lots of moons, have rings, further from sun 3. Asteroids and comets -far outnumber planets and moons , asteroid- rocky, majority orbit sun between mars and Jupiter , comet- icy, majority orbit the sun beyond Neptune 4. Exceptions -Uranus large axis tilt of 90 degrees, -Venus rotates backwards , - earth has large moon for terrestrial planet Formation of our universe 14 billion years ago the big bang occurred, mostly hydrogen and helium-100 million years later stars formed-stars are large nuclear reactors that produce heavy materials-when stars die they release heavy material-4.6 billion years ago our solar system formed
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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 .

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astro final guide - Celestial sphere-Position- it is...

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