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48 Cards in this Set
- Front
- Back
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Astronomy
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science that studies the universe
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The Greeks
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used philosophical arguments to explain natural phenomena
also used some observational data |
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Geocentric Model
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in the ancient Greeks' geocentric model, the moon, sun, ans the known planets -Mercury, Venus, Mars, and Jupiter - orbit the Earth
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Heloecentric Model
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Earth and the other planets orbit the sun
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Ptolemaic System
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Ptolomy created a model of the universe that accounted for the movement of the planets around the Earth (Geocentric)
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Nicolaus Copernicus
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concluded that the Earth is a planet
he proposed a model of the solar system with the sun at the center (Heliocentric) |
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Tycho Brahe
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designed and built instruments to measure the locations of the heavenly bodies
observations, especially of Mars, were far more precise than any made previously |
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Johannes Kepler
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discovered three laws of planetary motion
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Three Laws of Planetary Motion
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1. orbits of the planets are elliptical
2. planets revolve around the sun at varying speeds, faster when closer to the sun 3. there is a proportional relationship between a planet's orbit period and its distance to the sun |
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Galileo Galilei
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most important contributions were his descriptions of the behavior of moving objects
devoted his own telescope and made important discoveries |
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Sir Isaac Newton
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was the first to formulate and test the law of universal gravitation
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Universal Gravitation
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force decreases with distance
greater the mass of the object, the greater its gravitational force |
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Earth's Two Main Motions
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Rotation - spining on its axis
Revolution - moving around the sun |
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Precession
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third and very slow motion of Earth's axis
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Perigee
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point at which the moon is closest to Earth
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Apogee
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point at which the moon is farthest from Earth
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Solar Eclipses
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occur when the moon moves in a line directly between the Earth and sun, casting a shadow on Earth
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Lunar Eclipses
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occur when the moon passes through Earth's shadow
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Terrestrial Planets
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planets that are small and rocky
Mercury, Venus, Earth, and Mars |
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Jovian Planets
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huge gas planets
Jupiter, Saturn, Uranus,Neptune |
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Pluto
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doesn't fit into either the Jovian or Terrestrial categories
small ball of ice |
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Size
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most obvious difference between the terrestrial and Jovian planets
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Nebular Theory
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the sun and planets formed froma rotating disk of dust and gases
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Nebula
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cloud of gas and dust in space
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Mercury
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inner most planet
second smallest hardly larger than Earth's moon has greatest temperature extremes of any planet |
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Venus
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veiled planet
surface temperature reaches 450C and its atmosphere is 97% carbon dioxide (appears very bright) similar to Earth in size, density, mass, an location referred to as "Earth's Twin" |
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Mars
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red planet
martian atmosphere atmosphere is very thin extensive dust storms occur and may cause the color changes observed from Earth |
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Jupiter
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giant among planets
mass that is 21/2 times greater than the mass if all the other planets and moons combined has 300 year old storm known as the Great Red Spot |
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Saturn
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elegant planet
most prominent feature is its system of rings large cyclonic "storms" similar to Jupiter's Great Red Spot, but smaller occur in Saturn's atmosphere |
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Uranus
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sideways planet
instead of being perpendicular to the plane of its orbit like the other planets, Uranus's axis of roation lies nearly parallel with the plane of its orbit |
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Neptune
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windy planet
winds exceed 1000 kilometers per hour one of the windiest places in the solar system has a Great Dark Spot similar to Jupiter's Great red Spot (Hurrican Type Storm) blue appearance due to the presence of methane |
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Asteroid
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small, rocky body whose diameter can range from a few hundred kilometers to less than a kilometer
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Asteroid Belt
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most asteroids are located there
between the orbits of Mars and Jupiter |
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Comets
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small bodies made of rocky and metallic pieces held together by frozen gases
most famous if Halley's Comet (orbital period is 76 years) |
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Meteoride
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small, solid particle that travels through space
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Meteor
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the luminous phenomenon obserevd when a meteoroid enters Earth's atmosphere and burns up
popularly called a "shooting star" |
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Meteorite
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any portion of a meteoroid that reaches Earth's surface
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Constellation
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an apparent group of stars originally named for mythical characters
the sky containse 88 constellations |
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Star Color and Temperature
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Blue -very hot
Yellow - medium Red -cooler |
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Protostar
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a collaosing cloud of gas and dust destined to become a star
developing star not yet hot enough to engage in nuclear fussion when it core has reached 10 million Kelvin pressure within is so great the nuclear fusion of hydrogen begins |
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Main-Sequence Stage
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star spends 90% of its life in the main-sequence stage
our sun is currently in this stage |
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Red Giant Stage
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star's outer envelope expands
surface cools and becomes red eventually all nuclear fuel(hydrogen) is used and gravity squeezes the star all stars eventually run out of fuel and collapse due to gravity |
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Black Holes
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massive star that has collapsed to such a small volume that its gravity prevents the escape of everything, even light
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Galaxy
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group of stars, dust, and gases held together by gravity
Earth is in the Milky Way |
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Spiral Galaxies
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about 30% of all galaxies are spiral galaxies
our galaxy is a spiral galaxy |
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Elliptical Galaxies
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about 60% of galaxies are classified as elliptical galaxies
range from round to oval |
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Irregular Galaxies
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only 10% of the known galaxies have irregular shapes and are classified as irregular
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The Big Bang Theory
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states that at one time, the entire universe was confined to a dense, hot, super massive ball
then, about 13.7 billion years ago, a violent explosion occurred, hurling this material in all directions |
