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136 Cards in this Set
- Front
- Back
- 3rd side (hint)
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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 |
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
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Angular Size
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The size of an object in relation to your field of view. The Moon is about 1/2 degree.
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Size in FOV
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Angular Distance
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Distance that separates objects
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Arcminutes
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Subdivide each degree into 60 arcminutes
34 degrees, 43 arcminutes, 32 arcseconds |
34,>>>43<<<,32
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Arcseconds
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Subdivide each arcminute into 60 arcseconds. 34 degrees, 43 arcminutes, 32 arcseconds
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34,43,>>>32<<<
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Latitude
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North to South measurements. North Pole is 90^N degrees, South is 90^S degrees. Across the Earth
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Across
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Longitude
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East to West measurements. Greenwich, UK is 0^. Down and Up the Earth.
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Down and Up
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Prime Meridian
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The Longitudal line at Greenwich, UK. Is 0^
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Circumpolar
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Near the North and South Poles, stars do not set, but make clockwise circles in the sky
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Attitude of the Celestial Pole
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Is equal to your latitude
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Zodiac
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Path on the ecliptic that passes 13 constellations
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Winter Solstice
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Northern Hemi receives it's least direct sunlight. Southern Hemi receives it's most direct sunlight. Around December 21 each year.
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Spring Equinox
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Sun shines equally on both hemispheres. Around March 21.
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Summer Solstice
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Northern Hemi receives most direct sunlight. Southern receives least direct sunlight. Around June 21 each year.
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Fall Equinox
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Sun shines equally on both hemispheres. Around September 21.
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At what time is the Sun directly overhead?
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Trick question, it is never directly above unless you're in the tropics.
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Precession
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Gradial change in the direction of Earth's axis in space. Only orientation that changes, Earth will remain at 23 1/2 degrees. Earth will point to Vega instead of Polaris.
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Change of direction
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Lunar Phases
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Which direction the light hits the Moon, causing shadows on certain sides.
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Eclipse
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Anytime an object casts a shadow on another
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Nodes
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Two points in each orbit at which the Moon crosses the surface
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Moon and Eclipses
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Lunar Eclipse
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When Moon passes in Earth's shadow
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Solar Eclipse
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When Earth passes in Moon's shadow
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Umbra
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Where sunlight is completely blocked by Moon in a Solar Eclipse
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Penumbra
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Where sunlight is slightly blocked by Moon in a Solar Eclipse
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Saros Cycle
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Eclipses occur in an 18 years, 11 1/3 day period
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18 years, 11 1/3 days
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Retrograde Motion
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When a planet appears to go backwards because the Earth is in a tighter orbit than the outer planets from Earth.
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Stellar Parallax
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Apparent shifting of objects from different view points
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Shifting of objects
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Planet
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Means "wanderer"
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Egyptians
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Created a 24 hour day with 12 hour parts. Used water clocks.
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Time
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Stonehenge
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In Southern England. Created in 2750 B.C. to 1550 B.C. Sun rises directly over only on Summer Solstice.
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Templo Mayor
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In Aztec city of Tenochtitlan. Sun rose directly through the notch between the twin temples on the equinoxes.
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Metonic Cycle
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Every 19 years we get the same lunar cycles
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Lunar cycles
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Eratosthenes
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Measured the Earth accurately in 240 BC.
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Measured something
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Geocentric Model
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Earth as center of the universe
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Aristotle
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384 BC - 322 BC. Famous scientist.
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Ptolemy
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His book, the Almagest described a Earth-centered model that remained in use many years later
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Almagest
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Plato
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Heavenly spheres and circles
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Ptolemaic Model
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Planets made "small circles" in orbit explaining retrograde motion.
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Copernicus
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Sun-centered solar system. Used AU to measure distances. Still believed in perfect circles of orbit.
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De Revolutionibus Orbium Caelestium
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Tycho Brahe
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Kept records of universe. Best naked-eye records. Hired Johannes Kepler.
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Records
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Johannes Kepler
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Discarded perfect circles. Orbits were ellipses and circles.
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Foci
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Two points to draw an ellipse.
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Ellipse
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Eccentricity
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How much a planet deviates from a perfect circle
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Circle and ellipses
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Kepler's First Law of Planetary Motion
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The orbit of each planet about the Sun is an ellipse with the Sun at the one Focus.
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Ellipse
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Perihelion
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Closes to the Sun
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Close
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Aphelion
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Farthest point from the Sun
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Farthest
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Semimajor Axis
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Average distance from the Sun
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Kepler's Second Law of Planetary Motion
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As a planet moves around its orbit, it sweeps out equal areas in equal times.
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Equal areas
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Kepler's Third Law of Planetary Motion
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More distant planets orbit the Sun at a slower average speed, obeying the following precise mathematical relationship:
p^2 = a^3 where p is planet's orbital period in years and a is its average distance from the Sun in astronomical units. |
p^2 = a^3
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Galileo
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Used the telescope. Found:
1. Sunspots on the Sun 2. Moon has mountains and valleys by looking at shadows 3. Strong evidence of stellar parallax 4. Jupiter had moons too 5. Phases of Venus |
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Scientific Method
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Observations
Question Hypothesis Prediction Test |
OQHPT
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Discovery Science
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Going out and looking at nature to find something new
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Hypothesis-driven Science
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Proposing an idea and testing it
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Hypothesis
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An "educated guess."
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Occam's Razor
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When we choose the simpliest answer
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Theory
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Explain a wide-range of observations
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Wide-range
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Pseudoscience
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Based off evidence not treated scientifically
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Paradigm
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Ideas that fall outside mainstream thought
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Sidereal Day
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23 hours, and 56 minutes. When the Earth makes one full rotation
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23 hours...
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Solar Day
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24 hour-day, based off the time it takes the Sun to make one rotation
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Earth's Day Orbital Motion
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1 degree, makes a 360 degree orbit in 365 days
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360 degrees in one year
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Synodic Month
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When the Sun and Moon "meet" in the sky with every new moon. 29 1/2 days
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Sidereal Month
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Moon's true orbital period, 27 1/3 days
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Sidereal Year
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Time it takes to complete one orbit relative to the stars
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Stars
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Tropical Year
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Cycle of seasons, 20 minutes shorter than sidereal year
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Seasons
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Sidereal Period
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Time it takes to orbit the Sun
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Synodic Period
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Time between being lined up with the Sun
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Conjunction
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When planets line up with the Sun
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Lined Up
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Opposition
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Opposite of the Sun, away from the Earth
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Transit
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Transit across the Sun
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Greatest elongation
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Farthest from the Sun
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Apparent Solar Time
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The Sun's actual position in the sky, using a sundial.
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Mean Solar Time
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The average of solar times. 12:00 for a sundial would not match up with a watch. Uses the average of 12:00 to tell time.
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Standard Time
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Time zones
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Daylight Saving Time
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1 hour ahead
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Universal Time
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Also called GMT, UTC, or Zulu. Greenwich's central time.
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Leap Year
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In the Julian Calendar, every fourth year has 366 days.
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Gregorian Calendar
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Leap years are skipped unless the century is divisible by 400
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Pope Gregory XIII
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Declared after Oct 4 would be Oct 15
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Oct 15
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Celestial Coordinates
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Used to pinpoint locations on the celestial sphere
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Declination
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Similiar to Latitude
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Lat
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Right Ascension
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Similiar to Longitude
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Long
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Tropic of Cancer and Capricorn
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Boundary of where the Sun aims straight down
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Kepler's Third Law Formula
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p^2 = a^3
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Mass-energy conversion
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E=mc^2
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Kepler's Third Law According To Newton
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(m1 + m2)[Sun takes most room, planet is insignificant, it is 1] p2 = a3
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Kinetic energy
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v = SQRT (2G*M/R)
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