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205 Cards in this Set
- Front
- Back
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a large, glowing ball of gas that generates heat and light through nuclear fusion in it's core
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star
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a moderately large object that orbits a star and shines primarily by reflecting light from it's star. It should 1) orbit a star, 2) is massive enough for it's own gravity to give it a round shape, and 3) has cleared the neighborhood around it's orbit
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planet
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an object that 1)orbits a star, 2) is massive enough for it's own gravity to give it a round shape, and 3) has not cleared the neighborhood around it's orbit
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dwarf planet
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an object that orbits a planet.
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moon
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any object that orbits another object
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satellite
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a relatively small and rocky object that orbits a star
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asteroid
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a relatively small and ice-rich object that orbits a star
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comet
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an asteroid, comet, or other object that orbits a star but is too small to qualify as a planet or dwarf planet
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small solar system body
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the sun and all the material that orbits it, including planets, dwarf planets, and small solar system bodies
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solar system
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a star (sometimes more than one star) and any planets and other materials that orbit it
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star system
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a great island of stars in space, containing from a few hundred million to a trillion or more stars, all held together by gravity and orbiting a common center
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galaxy
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a gigantic region of space where many individual galaxies and many groups and clusters of galaxies are packed more closely together than elsewhere in the universe
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supercluster
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the sum total of all matter and energy- that is, all galaxies and everything between them
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universe (cosmos)
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the portion of the entire universe that can be seen from Earth, at least in principle- has around 100 billion galaxies
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observable universe
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the average distance between Earth and the Sun, which is about 150 million kilometers. More technically, this is the length of the semi major axis of Earth's orbit
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astronomical unit (AU)
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the distance that light can travel in 1 year, 9.46 trillion kilometers
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light-year
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the spinning of an object around it's axis.
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rotation
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the orbital motion of one object around another
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orbit (revolution)
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the increase in the average distance between galaxies as time progresses
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expansion (of the universe)
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the process in which lightweight atomic nuclei smash together and stick (or fuse) to make heavier nuclei
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nuclear fusion
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oriented so that it points almost directly at a star called Polaris, North Star
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axis tilt
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Earth's orbital path that defines a flat plane
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ecliptic plane
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a region of the sky with well defined borders-configuration of stars named after an object, person, or animal-used to map the sky
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constellation
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the point directly over Earth's North Pole
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north celestial pole
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the point directly over Earth's South Pole
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south celestial pole
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a projection of Earth's equator into space, makes a complete circle around the celestial sphere
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celestial equator
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the path the sun follows as it appears to circle around the celestial sphere once a year. It crosses the celestial equator at a 23.5 degree angle, because that's the tilt of the Earth's axis
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ecliptic
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the sky as seen from wherever you happen to be standing
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local sky
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boundary between the earth and the sky
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horizon
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point directly over head
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zenith
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an imaginary half circle stretching from the horizon due south, through the zenith, to the horizon due north
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meridian
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2 ways to pinpoint the position of any object in the local sky
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direction (azimuth) & altitude
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the angle an object appears to span in your field of view
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angular size
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the angle that appears to separate a pair of objects in the sky
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angular distance
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subdivide each degree into...
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60 arcminutes
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subdivide each arc minute into..
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60 arcseconds
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stars that never rise or set but instead make daily counterclockwise circles around the north celestial pole.
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circumpolar
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measures north-south position
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latitude
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measures east-west position
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longitude
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0 degrees longitude- runs through Greenwich England
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Prime Meridian
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constellations along the ecliptic- set of 12 constellations that the sun & moon move through
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zodiac
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the moment when the northern hemisphere is tipped most directly towards the Sun
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summer solstice (June 21)
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the moment when the Northern hemisphere is tipped most directly away from the Sun
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winter solstice (December 21)
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the moment when the Northern Hemisphere goes from being tipped slightly away from the Sun to being tipped slightly towards the Sun
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spring equinox (March 21)
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the moment when the Northern Hemisphere first starts to be tipped away from the Sun
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Fall equinox (September 22)
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the moon moves through the sky and both it's appearance and the times it rises and sets change
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cycle of lunar phases
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the moon rotates on it's axis in the same amount of time that it takes to orbit Earth
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synchronous rotation
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when the Sun, Earth, and Moon fall into a straight line
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eclipse
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occurs when the Earth lies directly between the Sun and Moon, so that Earth's shadow falls on the Moon
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lunar eclipse
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occurs when the Moon lies directly btwn the Sun and Earth, so that the Moon's shadow falls on Earth. People living within the area covered by the Moon's shadow will see the Sun blocked or partially blocked from view
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solar eclipse
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the 2 points in each orbit at which the Moon crosses the surface
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nodes
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1 distinct region of the shadow of the Moon/Earth: central, where the sunlight is completely blocked
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umbra
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1 distinct region of the shadow of the Moon/Earth: surrounding, where sunlight is only partially blocked
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penumbra
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When the Sun, Earth, and Moon are nearly perfectly aligned, the Moon passes through Earth's umbra and we see..
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total lunar eclipse
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When only part of the full moon passes through the umbra
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partial lunar eclipse
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when the Moon passes ONLY through Earth's penumbra
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penumbral lunar eclipse
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occurs when the Moon is relatively close to Earth in it's orbit, the Moon's umbra touches a small area of Earth's surface
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total solar eclipse
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the time during which the Moon is entirely engulfed in the umbra
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totality
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surrounding the region of totality is a much larger area that falls within the Moon's penumbral shadow
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partial solar eclipse
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if the eclipse occurs when the Moon is relatively far from Earth in it's orbit, the Moon's slightly smaller angular size means it's umbral shadow may not quite reach Earth's surface
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annular eclipse
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the 2 periods of the year when the nodes of the Moon's orbit are nearly aligned with the Sun
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eclipse seasons
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the combination of changing dates of eclipse seasons and the 29.5 day cycle of lunar phases makes eclipses recur in a cycle of about 18 years 11 1/3 days
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saros cycle
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when the planets occasionally reverse course, moving westward through the zodiac
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apparent retrograde motion
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the even thought to mark the birth of the Universe
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Big Bang
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galaxies appear to be receding from us-more distant galaxies are receding faster from us than closer ones- gives a distance and a speed in order to calculate the age of the universe-raisin bread analogy
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Hubble law
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a gradual wobble that alters the orientation of Earth's axis in space
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precession
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angular size of the moon/sun
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.5 degrees
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angular size of your fist at arm's length
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10 degrees
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angular size of a finger at arms length
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1-2 degrees
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the apparent path the Sun takes through the constellations in the course of a year
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ecliptic
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time of year when the sun is highest in the sky
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summer solstice (+23.5 degrees)
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time of year when the sun is lowest in the sky
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winter solstice (-23.5 degrees)
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the tilt of the moon around the sun
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5 degrees- why we don't have an eclipse every month
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period of the moon with respect to the stars
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Sidereal- 27.3 days
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period of the moon with respect to the sun
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Synodic- 29.5 days
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the motion of one body around another
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revolution
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the turning of a body about it's axis
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rotation
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the angle between the orbital plane of a revolving body and some fundamental plane
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inclination
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large core to atmosphere ratio- few/no moons
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terrestrial planets
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small "core" to atmosphere ratio-rings-lots of moons
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jovian planets
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jovian planets
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jupiter, saturn, uranus, neptune
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terrestrial planets
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mercury, venus, earth, mars
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the position of a planet when it is opposite the sun in the sky-relative to the earth
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opposition
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a conceptual representation created to explain and predict observed phenomena
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scientific model
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spherical earth at the center of the universe
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geocentric model
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Ptolemy's model that still placed earth at the center of the universe but was different from the geocentric model
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ptolemiac model
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the study of ancient structures in search of astronomical connections
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archaeoastronomy
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a band of colors, as seen in a rainbow, produced by the separation of the components of light
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spectrum
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the ways that light and matter interact
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emission, absorption, transmission, reflection/scattering, transparent, opaque
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the distance between successive peaks or troughs
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wavelength
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the number of peaks or troughs passing a point per second (in units of Hz, or cycles per second)
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frequency
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(frequency) x (wavelength)
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speed of wave
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discrete unit of electromagnetic energy
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photon
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modern day science started in what 2 civilizations?
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Mesopotamia and Egypt (Greece people!)
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what 3 major innovations did greek philosophers develop?
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1)tried to understand nature instead of relying on supernatural explanations-worked to debate and challenge each other's ideas 2) used math to give precision to their ides 3) saw the power of reasoning from observation
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spurred the development of virtually all modern science and technology
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copernican revolution
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sun was the center of the universe-but heavenly motion occurred in perfect circles
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copernicus
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special type of oval that planets move around
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ellipse
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2 tacks that are used to draw an ellipse
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foci
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each half of the major axis
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semimajor axis
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a quantity that describes how much an ellipse is stretched out compared to a perfect circle
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eccentricity
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who came up with the idea of ellipses instead of perfect circles?
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Kepler
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Kepler's 1st law of planetary motion
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the orbit of each planet around the Sun is an ellipse with the Sun at one focus
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the point at which a planet is closest to the sun in it's orbit
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perihelion
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the point at which a planet is farthest from the sun it's orbit
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aphelion
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Kepler's 2nd law of planetary motion
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as a planet moves around it's orbit, it sweeps out equal areas in equal times-a planet moves quicker when close to the sun and slower when far away from the sun
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Kepler's 3rd law of planetary motion
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more distant planets orbit the Sun at slower average speeds, obeying a precise mathematical relationship
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who invented (or made better) the telescope
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Galileo
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claims about the natural world that seem to be based on observational evidence but do not treat evidence in a truly scientific way
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pseudoscience
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what were the 2 benefits for astronomy in ancient cultures?
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1) to tell time 2) to predict the weather
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who was credited for developing the scientific method?
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Greeks
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who was the first astronomer?
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Thales
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who suggested the idea of a celestial sphere?
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Anaximander
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the Earth is a sphere within a celestial sphere. The reasoning was that the sphere is geometrically perfect.
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Pythagoras
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the Earth's curved shadow during lunar eclipse proves that the Earth is spherical
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Aristotle
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first to suggest that the Earth orbits the Sun
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Aristarchus
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the apparent displacement of an object caused by the motion of the observer
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Parallax
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How do we know that the Moon is closer to us than the sun?
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solar eclipses- the moon being closer blocks the light from the sun
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the earth is more or less what shape?
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cylindrical
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the Earth's radius is what times the Moon's radius?
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3
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Real numbers for sizes:
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The Sun is 400 times the size of the Moon & 100 times the size of the Earth
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Sun passes directly overhead at summer solstice
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Syene
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Sun comes within 7 degrees of zenith at summer solstice
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Alexander
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Introduced circles upon circles to explain retrograde motion
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Apollonius
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developed many of the ideas of the ptolemaic model, discovered precession, invented the magnitude system for describing stellar brightness
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Hipparchus
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Sun centered universe- but thought planet's motions were perfect circles
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Copernicus
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built an observatory for the naked eye observations to make accurate measurements of the positions of stars and planets
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Tycho
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the measurements of the positions of astronomical objects, was necessary to pave the way to the correct model
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astrometry
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apprentice of Tycho
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Kepler
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geosynchronous satellites' orbital period:
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24 hours-to keep them in sync with Earth's rotation
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tested gravitational acceleration by simultaneously dropping 2 different size masses from the top of the Tower of Pisa
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Galileo
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Tycho observed a comet & a supernova, evidence that the heavens are not static
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unchanging heavens
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sunspots and mountains on the Moon show deviations from perfect
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perfection
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Galileo used a telescope to resolve the Milky Way into faint stars; stars are farther away and more numerous than Tycho & others believed
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Lack of parallax
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the intellectual & practical activity encompassing the systematic study of the structure & behavior of the physical & natural world through observation & experiment
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science
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the simplest explanation is likely to be the correct one
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Occam's Razor
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a model that makes predictions that survive repeated & varied testing
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theory
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the apparent positions of the Sun, Moon and planets among the stars in our sky influence human behavior
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astrology
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3 important things in astrology
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1)there is a special meaning in the patterns of the stars in the constellations 2) the position of the planets among the constellations is important 3) a proper horoscope accounts for the positions of all planets
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makes hurricanes spin counter-clockwise in the Northern hemisphere
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Coriolis effect
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the time period where it takes a star to go from the highest point in the sky one day to the highest point in the sky the next day
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sidereal day- 23 hours 56 mins
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based on the time it takes for the Sun to make one circuit around the local sky-how long it takes for the sun to go from the highest point in the sky one day to the highest point in the sky the next day
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solar day- 24 hours
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29.5 day period required for each cycle of the moon's phases to pass through
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synodic month-29.5 days
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the moon's true orbital period
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sidereal month- 27.5 days
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the time it takes for Earth to complete one orbit relative to the stars
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sidereal year
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calendar that's based on the cycles of the seasons, time from one spring equinox to the next
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tropical year
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the time a planet takes to orbit
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sidereal period
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the time between wen a planet is lined up with the Sun in our sky at one time and the next similar alignment
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synodic period
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as seen from Earth-when the planet will sometimes line up with the Sun
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conjunction
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as seen from Earth- when the planet will appear exactly opposite the Sun in our sky
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opposition
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when the inner planets appear farthest away from the Sun in our sky
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greatest elongation
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when Mercury or Venus appear to cross directly in front of the Sun
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transit
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when time is based on the Sun's ACTUAL position in the local sky
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apparent solar time
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function like longitude and latitude in the celestial sphere
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celestial coordinates
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longitude on the celestial sphere
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Right ascension (RA)
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latitude on the celestial sphere
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declination (dec)
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23.5 N degrees
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tropic of Cancer
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23.5 S degrees
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tropic of capricorn
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66.5 N degrees
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Arctic Circle
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66.5 S degrees
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Antarctic Circle
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how fast something will go in a certain amount of time
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speed
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both speed and direction
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velocity
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if velocity changes in anyway
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acceleration
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acceleration of a falling object
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acceleration of gravity (9.8 meters per second)
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the product of mass x velocity
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momentum
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only way to change an object's momentum
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apply force
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represents the combined effect of all the individual forces put together
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net force
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special type of momentum winning staying in the same place but rotating
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angular momentum
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amount of matter in your body
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mass
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depends on your mass and the force of gravity
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weight
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type of force that can change angular momentum "twisting force"
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torque
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falling without any resistance to slow you down
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free fall
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when you float freely and the scale would read 0
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weightless
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3 laws that apply to all of motion
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Newton's laws of motions
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Newton's first law of motion
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an object moves at constant velocity if there is no net force acting upon it
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Newton's second law of motion
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force=mass x acceleration (F=ma) (force= rate of change in momentum)
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Newton's third law of motion
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for any force, there is always an equal and opposite reaction force
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states that the total momentum of interacting objects cannot change as long as no external force is acting on them
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conservation of momentum
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states that as long as there is no external torque, the total angular momentum of a set of interacting objects cannot change
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conservation of angular momentum
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energy cannot appear out of nowhere and can't disappear into nothingness
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conservation of energy
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energy of motion
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kinetic energy
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energy carried by light
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radioactive energy
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stored energy
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potential
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the collective kinetic energy of many individual particles (atoms and molecules) moving randomly within a substance like a rock or the air or the gas within a distant star
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thermal energy
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measures the average kinetic energy of the particles
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temperature
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what measures temperature in science
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Kelvin
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depends on the mass and how far it can fall as a result to gravity
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gravitational potential energy
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the energy contained in mass itself
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mass-energy
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universal law of gravitational
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1)every mass attracts every other mass through the force called gravity 2)the strength of the gravitational force attracting any 2 objects is directly proportional to the product of their masses 3)the strength of 2 objects decreases with the square of the distance between their centers.
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the strength of 2 objects decreases with the square of the distance between their centers
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inverse square law
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orbit in which the object goes around another object over and over again
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bound orbits
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paths that bring an object close to another object just once
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unbound orbits
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allowed orbital paths
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ellipses, parabolas, and hyperbolas
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the point at which the 2 objects would balance if they were somehow connected
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center of mass
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this equation allows us to measure orbital period and distance in any units we wish
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Newton's version of Kepler's 3rd Law
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the sum of a planet's kinetic and gravitational potential energies
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orbital energy
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when 2 planets or whatever pass near enough so that each can feel the effects of other's gravity
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gravitational encounter
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the minimum velocity required to escape Earth's gravity if a spacecraft starts near the surface
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escape velocity (11 km/s-->Earth)
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stretches the entire Earth to create 2 tidal bulges-one facing the moon and one opposite the moon
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tidal force
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when tidal forces stretch Earth itself and causes friction
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tidal friction
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the moon always shows (nearly) the same face to Earth
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synchronous rotation
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the momentum something has while spinning on it's axis
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angular momentum
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developed calculus
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Isaac Newton
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you don't feel motion when moving at a constant speed
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inertia
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what are conic sections?
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circles, ellipses, parabolas, and hyperbola
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