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41 Cards in this Set
- Front
- Back
Right Ascension
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The angular distance measured eastward around the sky from the vernal equinox.
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Declination
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The angular distance measured north or south from the celestial equator.
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Laws of Physics
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Approximate descriptions of what is observed in the physical world.
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Degrees
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1/360th of the circumfrence of a circle.
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Arcminute
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1/60th of a degree.
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Arcsecond
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1/60th of an arcminute, or 1/3600th of a degree.
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Celestial Equator
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The great circle on the celestial sphere, every point of which is exactly 90 degrees from the celestial poles.
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Vernal Equinox
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A point on the celestial sphere which astronomers use as the origin of the celestial coordinate system.
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Astronomy
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The study of extraterrestrial bodies and related aspects of the physical universe.
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Physical Universe
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Everything that can be sensed, measured, or observed.
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The Solat System
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A gravitationally bound system consisting of the Suna and all its satellites. Radius = 1 LY
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The Solar Neighborhood
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All of the stars within 100 parsecs of the Sun (or Solar System).
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The Milky Way Galaxy
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A gigantic, gravitationally bound system consisting of about 200 billion stars, including the Sun and Solar Neighborhood.
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The Local Group
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A gravitationally bound cluster of about 28 or so galaxies, including the Milky Way Galaxy.
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The Supercluster
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A cluster of many smaller clusters of galaxies, including our Local Group.
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The Universe, or Cosmos
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The largest scale of physical reality, consisting of other clusters and superclusters of galaxies, extending in a frothy-like distribution to the limit of visibility.
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Meter (m)
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One millionth of the distance between the pole and the equator of the Earth.
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Kilometer (km)
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One thousand meters
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Astronomical Unit (AU ot au)
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The average or mean distance of the Earth from the Sun.
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Light Year
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The distance that light travels in the time of one year.
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Parsec (pc)
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When the Earth is one parsec from the Sun, the Earth's orbital radius subtends an angle of 1 arcsecond.
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Rotation
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The motion of a body around and imaginary axis which passes through that body.
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Revolution
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The orbital motion of a body around a point called the center of gravity, or barycenter.
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Precession
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The wobbling motion of the axis of rotation.
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Terrestrial- Lunar Motion
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The Earth and Moon interact gravitationally in such a way that their individual centers revolve around a common center of gravity once every 27.33 days, or one sidereal month.
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Planet
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A type of body that moves in orbit around a star.
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Star
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A very hot, usually gaseous body that generates, or at one time did generate, energy through thermonuclear fusion of hydrogen into helium.
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Mass
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The amount of matter in a body.
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Size
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The dimension of a something, such as raduis, diameter, or volume.
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Density
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The amount of mass in a given volume.
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Satellite
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A body which moves in orbit around another more massive body.
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Weight
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An expression of the force of gravity between an object and another body.
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Force
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Something that causes an acceleration or change in velocity of an object.
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Gravity
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The force of attraction that exists between any two physical objects.
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Electromagnetism
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The force that dictates the structure and workings of an atom (the arrangement of electrons around the nucleus) and the interaction of radiation with matter.
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Nuclear or Strong Force
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The force that dictates the structure and workings of the nucleus of an atom, including nuclear reactions
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The Weak Interactions
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The force that expresses the interaction of subatomic particles including radioactive decay.
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Newton's First Law of Motion (the Law of Inertia)
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A motion of an object will remain constant until it is acted on by an unbalanced force.
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Newton's Second Law of Motion
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When an unbalanced force acts on an object, it produces an acceleration. The more massive the object, the smaller the acceleration will be. (a=f/m)
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Newton's Third Law of Motion
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When any two objects interact, they exert equal but oppositely directed forces on one another.
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The Celestial Sphere
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An imaginary sphere with the Earth at its center on which every object in the sky has a location
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