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what is the universe composed of?
empty space, energy and matter
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most of the universe is _________
empty space
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whawt does matter in the universe include?
gas molecules, mainly hydrogen, and dust particles
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some of this matter had come together to form______
stars, planets, moons, asteroids, meteoroids and comets
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most of these objects can only be seen with a ___
telescope or other scientific instruments
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define stars
spherical masses of hot gases that produce energy
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why do stars look small?
because they are far away
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what units do astronomers use to measure the distance of stars?
light years
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define a light year
the distance light travels in a year
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Is our universe expanding?
yes
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most stars and galaxies of stars are moving ________
away from each other
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how old is the sun estimated to be?
4.5 billion years old
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what is the central and largest body of our solar system?
the sun
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what si the nearest star to earth?
the sun
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the sun is considered an _________ sized star
average
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what color is the sun?
yellow
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what are some features on the sun's surface?
eruptions called solar flares and sun spots
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what are the brightest stars called?
blue giants
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what color are the coolest stars?
red
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compared to a red dwarf, a white dwarf is ________
hotter and brighter
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what is the sun classified as?
a main sequence star
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light, heat, and ultraviolet radiation are types of _______produced be stars
energy
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what is the most common gaseous element found in stars?
hydrogen
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define planets
solid bodies which move in definite paths around a central star
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what keeps the planets in orbit around the sun?
gravity
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what are the two types of planets in our solar system?
terrestrial and jovian
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what are the inner planets called?
terrestrial planets
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what are the outer planets called?
jovian planets
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describe the inner planets
small dense and rocky
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describe the outer planets
large gaseous and have low densities
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what are the shapes of planets?
spherical
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what is the name of the almost (but not quite) circular orbit planets and other objects take around the sun?
elliptical orbit
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jovian planets have _____ moons than terrestrial planets
more
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define asteroids
large irregular shaped rocks that orbit the sun
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what is located between mars and jupiter?
asteroid belt
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define comets
masses of ice and embeded rock debris
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what is the ice fromt eh comets made from?
water, ammonia, methane, and carbon dioxide.
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whwat happens as a comet gets closer to the sun?
it will begin to warm and vaporize
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as the comets melts it leaves behind a trail of ______
rock debris
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what does the rock debris from a comet become?
meteoriod
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define meteoroid
rock fragments in space that can be as big as a boulder or as small as dust
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when meteoroids and asteroids hit moons or planets what does it form?
a crater
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define moons
solid objects which orbit around planets
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the phrase "dirty snowball could best describe a_______
comet
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what is the smallest planet?
mercury
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what is the largest planet?
jupiter
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what planet has the longest revolution?
neptune
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which planet had similar density as earth?
mercury
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which planet has similar size as earth?
venus
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the moon is a ___________ of earth
natural satellite
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what is the period of revolution and rotation?
27 1/3 days
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why does the same side of the moon always face the earth?
because the rate of rotation and revolution is the same
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why do we see the moon?
because it reflects light off the sun
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what causes us to see the moons different phases?
the moons revolution around earth
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what is the order of the planets?
mercury, venus, earth, mars, jupiter, saturn, uranus, neptune
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what is the order of the moons phases?
new moon, waxing crescent, first quarter, waxing gibbous, full moon, wanning gibbous, last quarter, wanning crescent, new moon
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what causes eclipses?
the interactive movements of the moon and earth relative to the sun
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when do eclipses occur?
when the sun, moon and earth are exactly lined up
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what is the order of the moon sun and earth during a solar eclipse?
the moon is in between the sun and earth (sun, moon, earth)
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what is not visible during a solar eclipse?
the sun
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why is the sun not visible during a solar eclipse?
because the moons shadow falls on earth
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what is the order of the moon sun and earth during a lunar eclipse?
the earth is in between the sun and the moon (sun, earth, moon)
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what is not visible during a lunar eclipse?
the moon
-
why is the moon not visible during a lunar eclipse?
because the earths shadows falls on the moon
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define tides
cyclic pattern of water rising and falling along the ocean shoreline
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what causes tides?
the gravitational pull of the moon and sun on the earths ocean
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what has more effect on tides, the sun or the moon? why?
the moon because its closer
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