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134 Cards in this Set
- Front
- Back
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Earth and the sun are part of a cast collection of matter called the Milky Way _______.
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galaxy
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The apparent path of the Sun across the sky is known as the _______.
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eplictic
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On December 21, known as the _______, the Sun is at its _______ point on the celestial sphere.
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winter solstice
lowest |
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The solar day is measured relative to the Sun; the sidereal day is measured relative to the _______.
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stars
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To explain the daily and yearly motions of the heavens, ancient astronomers imagined that the Sun, Moon, stars, and planets were attached to a rotating _______.
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celestial sphere
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Declination measures the position of an object north or south of the _______.
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celestial equator
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A _______ eclipse can be seen by about half of Earth at once.
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lunar
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How and why does a day measured by the Sun differ from a day measured by the stars?
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solar day is longer than a sidereal day
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Why do we see different stars in summer than in winter?
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earth's axis is in a different direction, it is completely opposite in the winter
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Why are there seasons on Earth?
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tilt of earth causes different heat on earth
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If one complete hemisphere of the Moon is always lit by the Sun, why do we see different phases of the Moon?
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earth covers the moon sometimes, the moon is not ecliptc
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Why aren’t there lunar and solar eclipses every month?
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they are rare instances
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What is precession, and what is its cause?
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precession is the tilt of the earth's axis over many centuries and it causes different positions of eath over years. tilt---23.5% degree
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When the planets Mars, Jupiter, and Saturn appear to move "backwards" (westward) in the sky relative to the stars, this is known as _______ motion.
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retrograde
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The geocentric model holds that _______ is at the center of the solar system.
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earth
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Galileo discovered _______ of Jupiter, the _______ of Venus, and the Sun’s rotation from observations of _______.
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moons
phases sunspots |
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Kepler’s laws were based on _______'s observations.
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Brahe's
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Kepler discovered that the shape of an orbit is an _______, not a _______ as had previously been believed.
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elliptical
circular |
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According to Kepler’s first law, the Sun lies at the _______ of a planet’s orbit
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focus
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. Kepler’s third law relates the _______ of the orbital period to the _______ of the semi-major axis.
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square
cube |
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Newton’s first law states that a moving object will continue to move in a straight line with constant speed unless acted upon by a _______.
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another force
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Newton’s law of gravity states that the gravitational force between two objects depends on the _______ of their masses and inversely on the _______ of their separation.
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product
square |
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Briefly describe the geocentric model of the universe.
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earth at the center of the universe
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What was the basic flaw in the Ptolemaic model of the universe.?
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earth isn't center of the solar system
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What was the great contribution of Copernicus to our knowledge of the solar system?
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helped described reasons stars followed paths that resembled geocentric model
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What was the Copernican Revolution?
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when Copernicus relooked at heliocentric mofel of Aristarchus
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State Kepler’s first law of orbital motion.
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Law #1: orbital paths are elliptical, not circular
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State Kepler’s second law of orbital motion.
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Law #2: imaginary line connecting the sun sweeps out equal areas of the ellipse
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State Kepler’s third law of orbital motion.
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Law #3: P (Squared) = a (cubed)
planet's oribtal period (^2) = (semi-major axis)^3 |
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What would happen to earth if the sun's gravity was suddenly "turned off"?
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the orbit of the earth would move in a straight line
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A lunar eclipse can occur only during the full phase.
a. True b. False |
true
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Solar eclipses are possible during any phase of the Moon.
a. True b. False |
false
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The constellations lying immediately adjacent to the north celestial pole are collectively referred to as the zodiac.
a. True b. False |
false
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The light-year is a measure of distance.
a. True b. False |
true
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The solar day is longer than the sidereal day.
a. True b. False |
true
solar day = 365.242 days sidereal day= 365.256 days |
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The stars in a constellation are physically close to one another.
a. True b. False |
false
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The vernal equinox marks the beginning of fall.
a. True b. False |
false
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The size of Earth's radius is close to ___ times the size of the Moon's radius.
a. 2 time b. 4 times c. 6 times d. 20 times |
b. 4 times
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Seasons are caused by:
a. Earth's changing distance from the Sun during its orbit. b. changes in the sun. c. the tilt of Earth's axis. d. none of the above |
c. tile of earth's axis
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The 12 zodiacal constellations lie along the ___.
a. ecliptic b. Earth's axis c. plane of Earth's orbit d. none of the above |
a. ecliptoc
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. The times during the year when the sun is at equal distances from the Earth's poles are called:
a. solstices b. equinoxes c. both d. neither |
b. equinoxes
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Night and day have approximately equal length at what time or times of the year?
a. summer equinox b. winter solstice c. summer solstice d. vernal and autumnal equinoxes e. winter equinox |
d. vernal and autumnal equinoxes
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What is the length of time needed for the Earth's rotation axis to complete one cycle of precession?
a. 1,000,000 years b. 26,000 years c. 365.256 days d. 365.242 days e. 29.5 days |
b. 26, 000 years
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what is the celestial shphere?
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a canopy of starslike an astronomical painting on a heavenly ceiling.
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what is a rotation?
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it constitutes as the earth's rotation
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what is the north celestial pole?
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the point at which earth's axis intersects at Northern Hemisphere
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what is the south celestial pole?
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the point at which earth's axis intersects of at south celestial sphere
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what is the celestial equator?
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the intersection of the earth's equalateral plane
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what are celestial coordinates?
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latitude and longitude of celestial sphere
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what is declination?
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the latitude of CS
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What is right acension?
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the longitude of CS
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What is a solar day?
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day followed by sun
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what is a diurnal motion
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daily progress of sun and stars across sky
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what is a sidereal day?
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a day measured by the stars
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what is an ecliptic?
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apparent motion of sun on the sky traces the path of celestial sphere
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what is the zodiac?
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the constellations the sun passes, astrologists used this.
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what is summer solstic?
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the point at which the sun is at its northernmost point
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what is winter solstice?
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the point at which sun is at its most southern point
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what are seasons?
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marked difference between temperature of hot and cold season
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what are equinoxes?
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day when nighttime is equally the same length of time as daytime
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what is an autmnal equinox?
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when the sun crosses from the northern to the southern celestial hemisphere
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what is a vernal equinox?
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occurs in the spring, whjen the sun crosses the celstial equator moving north
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what is a sidereal year?
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time for the earth to orbit around the sun once
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what is a precession?
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the change in direction of earth's axis over time
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what are phases?
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changes in the moon
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what does the new moon look like?
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it is not visible
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when does the quarter moon occur?
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1 week into phase
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what is the moon sidereal month?
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27.3 days around earth
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what is a syondic month?
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month for moon to complete all its phases in 29.5 days
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what is a lunar eclipse?
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when earth covers the moon
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what is a partial?
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only a little
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what is a total eclipse?
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fully covering moon
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what is an umbra?
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the central region of the eclipse, the shadow
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what is the penumbra?
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some of the sun's light
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what is the annular eclipse
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when the moon covers the son
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what is a baseline?
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the baseline of a trianglatioj
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what is triangulation?
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finding distance of things through method of a triangl, invented by Euclid
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what is a cosmic distance scale?
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scale made up from triangulation
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what is a parallax?
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displacement between foreground object relative to background
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what is a theory?
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a framework of idease used to explain some set of the world
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what is retrograde?
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backwards motion of planets?
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what is geocentric?
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earth lay at center of universe
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what is a epicycle?
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cycle of indiviual planet's with Aristole's view of the universe's orbit
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what is a deferent?
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orbit in which planets followed within geocentric veiw
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what is the ptolemaic model?
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model of the stars as based on Greek astronomer Claudis Ptolemeause, who believed that tehre were more than 80 celestial beings orbiting the earth
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what is helocentric mean?
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sun centered
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what is the copernican revolution?
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the critical realization that a 16th century Polish cleric, Nicolas Copernicus, had once rediscovered the writing of Aristarchus regarding the heliocentricmodel
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wwhat is an ellipse
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a flattened circle
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what is a focus?
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a point in a ellipse
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what is eccentricity?
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distance between foci/length major axis
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what is perhelion?
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its point of closer approach to the sun
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what is aphelion?
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greatest distance from the sun
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What is Kepler's second law?
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an imaginary line connecting the sun to any planet sweeps out equal areas of the elli0pse in equal intervals of time.
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What is a period?
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defined as time needed for one planet to complete a one circuit around the sun
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what is Kepler's third law?
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the square of a planet's orbital period is preportional to the cube of its semi-major axis (P^2=a^3)
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what is astronomical unit?
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a unit custom made for the vast distance encountered in astronomy
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what does radar stand for?
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radio detection and ranging
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what is newtonian mechanics
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newton's theories
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what is interia?
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tendency of an object to keep moving at the same speed and in the same direction unless acted upon by a force
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what is acceleration?
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rate of change in velocity
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what is the center of mass?
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the "average" position of thematter comprisinig of two bodies
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At the vernal equinox there are 12 hours of light and 12 hours of night _________ in the world.
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everywhere
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when is the earth's vernal equinox?
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march 20th
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During a total eclipse of the moon, why isn't it dark?
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its due to infraction
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what is refraction?
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whaen light slips by earth onto the moon, light passses curve of earth.
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where is it always light at
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on the south pole
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where is it always dark?
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on the north pole
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when did Ptolemy exist, and what did he do?
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Ptolemy-87-150-Catholic church was trying very hard to keep calender
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what did Aristole believe?
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that orbits had to be in circles because everything had to be natural, a circle was the most natural path
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when did Copernicus live?
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1473-1543
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What was wrong with Copernicus's heliocentric path
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made planets move in circles, but thhey move on epicenters
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who was tycho brahe, when did he live, and what did he do?
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king of denmark gave him an island to do observations at. Got into a duel once, so he had a fabricated nose.
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How long was Tycho out on his island?
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twenty years
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how much of the gross domestic national product was spent on Tycho's island?
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5% of Dutch GNP
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What was funny about Brahe having his own island?
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he had no telescope!
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Who invented the telescope?
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Galileo
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Who was Kepler?
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1571-1630, went to work for Brahe when he was younger. Keply was the only one who knew how valuable the data was. Kepler didn't disagree with Galileo opn ideas of motion.
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Who was born the year Galileo died?
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Newton
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At what month in the year is earth the closest?
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January
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the farthest?
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July
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velocity=
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distance/time
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distance=
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(rate)(time)
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Netwon's first law?
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velocity is constant
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when you don't have acceleration, your velocity is
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constant
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Next force of an airplane traveling straight at 500 mph is what?
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zero
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what are the basic forces in nature, and who many are there?
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Four:
(1) gravity (2) strong force (3) electric (4) weak |
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who invented calculus?
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newton
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who influenced newton?
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kepler
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if something falls without air, how far would somehting fall in one second (including feathers)?
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10 meters/second
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What is responsible for keeping you on surface of earth?
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attraction between you and earth's mass
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when objects travel in circles, there must be a force on the object toward:
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the center of the circle
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F= G m m
__________ ___ |
r^2
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what does the speed of a sattlite depend on?
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the mass of the earth
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What laws are more basic? newton or keplers?
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newtons
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