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35 Cards in this Set
- Front
- Back
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What is the universe?
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totality of all space, time, matter, and energy
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What is astronomy?
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the study of the universe
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Give the characteristics of scientific theories.
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1. must be testable
2. must be continually tested 3. should be simple 4. should be elegant |
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what is declination?
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degreees north of south of celestial equator.
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what is right ascension?
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measured in hours, minutes, and seconds eastwards from position of the sun at vernal equinox
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finish the sentence.... stars seem to be on the...
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inner surface of a sphere surrounding the earth
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When do eclipses occur?
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when the moon, earth, and sun form a straight line.
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what is the summer solstice?
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the northernmost point above the celestial equator
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what is the winter solstice?
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the southernmost point below the celestial equator
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what are vernal and autumnal equinoxes?
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the points where path crosses elestial equator
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What is a tropical year?
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time from one vernal equinox to the next
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About how long ago did we figure the size of the earth?
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2200-2300 years ago
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what are the inferior planets?
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mercury and venus
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what are the superior planets?
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mars, jupiter, and saturn
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which planets orbits are closer to the sun than earth's?
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inferior
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what is kepler's first law?
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his first law states that every planet revolves around the sun in an orbit that is an ellipse with the sun at one focus.
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what is kepler's second law?
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a line from the planet to the sun will sweep out equal are in equal time.
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what is kepler's thrid law?
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the square of the period of a planet is equal to the cube of its semimajor axis.
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what does newton's laws of motion explain?
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they explain how objects interact with the world and with each other and the rest of the objects in the universe.
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what is newton's 1st law?
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momentum of an object does not change unless acted upon by a force. an object at rest will remain at rest, and an object moving in a straight line at constant speed will not change its motion, unless an external force acts on it. a body in motion will remain in motion in a straight line until acted upon by force.
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what is newton's 2nd law?
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when a force is exerted on an object, its acceleration is inversely proportional to its mass: a=F/m
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what is newton's 3rd law?
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when object A exerts a force on object B, object B exerts an equal and opposite force on object A.
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what is the definition of mass?
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mass is that property of matter that resiss the change of motion
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True/False. Gravity always pushes.
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False gravity always pulls and never pushes.
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what is the rule with two massive objects and their gravity?
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for two massive objects gravitational force is proportional to the product of their masses divded by the square of the distance between them.
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what is orbital velocity?
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that velocity whose centrifugal force just balances the gravitational force
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what are electromagnectic waves?
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oscillating electric and magnetic fields. changing electric field creates magnetic field, and vice versa.
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what is the wave speed of elctromagnetic waves?
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C=3.0 x 10^8 m/s
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what is a black object?
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a black object is a theroretical body that only radiates, and does not reflect. a black body can only be approximated.
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what is the doppler effect?
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if one is moving toward a source of radiation, the wavelengths seem shorter; if moving away, they seem longer.
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what is absorption spectrum?
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if a continuous spectrum passes through a cool gas, atoms of the gas will absorb the same wave lengths they emit
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what is image acquisition?
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charge coupled devices (CCDs) are electronic devices- can be read out and reset quickly
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consering telescope size what are reasons why larger telescopes are more desirable?
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1. larger telescopes have better resolution
2. larger telescopess can gather more light 3. light gathering power improves detail 4. brightness proportional to square of radius of mirror |
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true of false. radio telescopes are similar to optical reflecting telescopes
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true
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in order to study gamma rays, ultra rays, ultra red, you must be where?
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space
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