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ASTRONOMY REVIEW SESSION. Galileo. proved the sun was the center of the solar system (heliocentric) used a telescope phases of Venus : proved that Earth can NOT be in center because if it was then we’d see all of Venus all the time
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Galileo • proved the sun was the center of the solar system (heliocentric) • used a telescope • phases of Venus: proved that Earth can NOT be in center because if it was then we’d see all of Venus all the time • moons of Jupiter: proved not everything revolves around Earth
Aristotle • introduced the idea of elliptical orbits in geocentric theory
Copernicus • 1st astronomer to name the sun as the center of the solar system
Hershel • Invented the reflecting telescope • discovered Uranus
Kepler • Heliocentric theory with elliptical orbits • wrote 3 laws of planetary motion
Newton • explained gravity • wrote Principia
Solar System • smaller systems within a system (planets & moons) • formed from a nebula /sun took 99% of matter • inner planets are rocky because when sun was forming its heat / energy pushed lighter particles away but the heavier ones stayed closer became inner planets • outer planets are gas becausethe lighter particles pushed further out became outer gas giants
Two forces that keep planets balanced in orbit: • gravity: sun’s gravity pulls planets in • inertia: planet’s inertia pulls planets in straight line
Two forces that keep planets balanced in orbit: • if one force is missing, then: • gravity: inertia would pull planet out of straight line • inertia: gravity would pull planet towards the sun
head Comets • ball of ice & dust with long, stretched elliptical orbit • always points awayfrom sun • solar winds push tail away
Meteors • meteor • meteorite • meteoroid pieces of comets & asteroids
asteroids • Small and numerous • between Mars and Jupiter • May have been a planet that was destroyed somehow OR • Never formed into a planet because Jupiter’s gravity kept pulling the pieces apart
Sun • 5 billion yrs old; lives for 10 billion yrs • medium/average size • sunspot—cooler / dark /surface / 11 yr cycle • prominence—loops of gas connecting sunspot regions • flare—prominences collide / explosion of gas & radiation • nuclear fusion in core turns hydrogen helium; releasing heat & light
Parts of the sun • Corona • Outer halo • Usually not seen because photosphere is so bright • Core • Nuclear fusion • Hydrogen fuses into helium • Energy released • chromosphere • Middle layer • reddish • Usually seen at beginning or end of eclipse • Photoshpere • Surface/inner layer • Produces the light • Seen in a picture
Planets • Know the descriptive features/characteristics of each planet • EXAMPLES: • Tilted on its side, blue, discovered by Hershel = ?? • Uranus • Red, seasons, ice at poles, 2 moons = ?? • Mars