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Solar System
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Sun and all the objects that orbit it
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Milky Way Galaxy
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Our galaxy!!! Nice chocolate snack. 100 billions stars. Can be seen more easily in the South Hemisphere.
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Local Group
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Groups of galaxies
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Milky Way is one of two largest |
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Galaxy Clusters
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Groups of galaxies with more than a dozen members bound by gravity
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12 |
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Star
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Big hot ball of nuclear fusion
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Planet
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Large object that orbits a star
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Moon
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Object that orbits another object (asteroids can have moons too!!!)
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Asteroid
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Possibly small and rocky object that orbits a star
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Comet
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Possibly small and icy object that orbits a star
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Solar System
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Technically only applies to our system, however, stupid (sometimes smart too!) scientists sometimes apply it to other systems. Basically a star and its planets
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Galaxy
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Many stars orbiting a common center
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Supercluster
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Many galaxies and clusters are packed closely together
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Universe
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Everything out there. Appears to be expanding.
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Observable Universe
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Everything that can be seen. Only a small part
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Astronomical Unit (AU)
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Length of the semimajor axis of Earth's orbit (AKA, how far the Earth is from the Sun.) 150 million kilometers.
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Light-Year
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Distance that light can travel in a year. 9.46 trillion kilometers.
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9.46 |
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Rotation
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Spinning of an object around it's axis. One day = one rotation. Line between the North and South Pole. Earth rotates West to East.
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Day |
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Revolution
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How long it takes to go around a object. One Year = One Revolution. Travelling at about 60,000 miles per hour.
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Year |
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Expansion
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The universe is expanding. Individual galaxies and clusters are not.
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Big Bang Theory
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The universe started expanding. Not necessarily an explosion.
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Nuclear Fusion
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Stuff that makes stars hot and bright. Lightweight atomic nuclei smash together and stick together make heavier nuclei.
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Supernovae
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When a star runs out of fuel, it makes a big boom.
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The Orion Nebula
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Giant cloud of dust and gas in which new stars are forming. About 1,500 light years from Earth.
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Looking back in time
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The farther we look in the distance, the further back we look in time.
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Light travelling |
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Distance = speed X time
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1 light-year = (300,000km) X 1 year)
365 Days 24 Hr 60 min 60S
________ X _____ X ______ X ___
1 year 1 day 1 hr 1 min
= 9,460,000,000,000 km
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1 light year = speed X time |
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Ecliptic Plane
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Earth's orbit defined in a flat plane around the sun.
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Orbit |
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Earth's tilt
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23 1/2 degrees perpendicular to the ecliptic plane.
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Ellipse
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An orbit, which is not a perfect circle
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Movement relative to nearby stars
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70,000 kilometers per hour
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70 |
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Distant from galactic center
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28,000 light years.
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Galaxy's Halo
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Stars only a small part of galaxies. Mass of galaxies seem outside of visible spectrum (stars). Possible dark matter on the outsides
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Dark matter |
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Dark matter
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Stuff that's dark, makes up most of the mass of the universe, and not known what it is.
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Mass of the universe |
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Galactic Orbit
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230 million years
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230 |
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Milky War-Andromeda Collision
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Nearly 10 billion years away if it happens. Moving at 300,000 kilometers per hour.
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Galaxies outside of the local group
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Appears to be moving from us. The farther it is the faster it is moving
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Moving from us |
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Edwin Hubble
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Appears to be moving from us. The farther it is the faster it is moving
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Moving from us |
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Copernicus
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Sun-centered solar system in 1543
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1543 |
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Galileo
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Claimed Earth moved around the Sun. Put under house arrest in 1633 by the Vatican. Church realized it was wrong, realized Earth was round and went around Sun in 1992.
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Where is the center of the galaxy?
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Trick question, there is none
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Number of stars that can be seen with the naked eye
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2000-3000
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Constellation
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Specific region of the sky. IAU divides the sky into 88 constellations
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Great Celestial Sphere
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Greeks believed the Earth was surrounded by giant sphere of stars
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North Celestial Pole
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Giant Celestial Sphere right above the North Pole
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North Pole |
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South Celestial Pole
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Giant Celestial Sphere right below the South Pole
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South Pole |
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Celestial Equator
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Extension of Earth's Equator into space
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Ecliptic
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Path the Sun takes per year around Celestial Sphere
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Sun |
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Local Sky
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The "dome" of the sky we can see
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Dome |
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Horizon
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Boundary between the Earth and sky.
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Zenith
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Directly overhead, 90 degrees
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Meridian
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The half-circle from your north horizon to south horizon.
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Half-circle |
