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134 Cards in this Set

  • Front
  • Back
Earth and the sun are part of a cast collection of matter called the Milky Way _______.
The apparent path of the Sun across the sky is known as the _______.
On December 21, known as the _______, the Sun is at its _______ point on the celestial sphere.
winter solstice

The solar day is measured relative to the Sun; the sidereal day is measured relative to the _______.
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 _______.
celestial sphere
Declination measures the position of an object north or south of the _______.
celestial equator
A _______ eclipse can be seen by about half of Earth at once.
How and why does a day measured by the Sun differ from a day measured by the stars?
solar day is longer than a sidereal day
Why do we see different stars in summer than in winter?
earth's axis is in a different direction, it is completely opposite in the winter
Why are there seasons on Earth?
tilt of earth causes different heat on earth
If one complete hemisphere of the Moon is always lit by the Sun, why do we see different phases of the Moon?
earth covers the moon sometimes, the moon is not ecliptc
Why aren’t there lunar and solar eclipses every month?
they are rare instances
What is precession, and what is its cause?
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
When the planets Mars, Jupiter, and Saturn appear to move "backwards" (westward) in the sky relative to the stars, this is known as _______ motion.
The geocentric model holds that _______ is at the center of the solar system.
Galileo discovered _______ of Jupiter, the _______ of Venus, and the Sun’s rotation from observations of _______.


Kepler’s laws were based on _______'s observations.
Kepler discovered that the shape of an orbit is an _______, not a _______ as had previously been believed.

According to Kepler’s first law, the Sun lies at the _______ of a planet’s orbit
. Kepler’s third law relates the _______ of the orbital period to the _______ of the semi-major axis.

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 _______.
another force
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.

Briefly describe the geocentric model of the universe.
earth at the center of the universe
What was the basic flaw in the Ptolemaic model of the universe.?
earth isn't center of the solar system
What was the great contribution of Copernicus to our knowledge of the solar system?
helped described reasons stars followed paths that resembled geocentric model
What was the Copernican Revolution?
when Copernicus relooked at heliocentric mofel of Aristarchus
State Kepler’s first law of orbital motion.
Law #1: orbital paths are elliptical, not circular
State Kepler’s second law of orbital motion.
Law #2: imaginary line connecting the sun sweeps out equal areas of the ellipse
State Kepler’s third law of orbital motion.
Law #3: P (Squared) = a (cubed)

planet's oribtal period (^2)


(semi-major axis)^3
What would happen to earth if the sun's gravity was suddenly "turned off"?
the orbit of the earth would move in a straight line
A lunar eclipse can occur only during the full phase.

a. True b. False
Solar eclipses are possible during any phase of the Moon.

a. True b. False
The constellations lying immediately adjacent to the north celestial pole are collectively referred to as the zodiac.

a. True b. False
The light-year is a measure of distance.

a. True b. False
The solar day is longer than the sidereal day.

a. True b. False

solar day = 365.242 days

sidereal day= 365.256 days
The stars in a constellation are physically close to one another.

a. True b. False
The vernal equinox marks the beginning of fall.

a. True b. False
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
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
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
. 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
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
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
what is the celestial shphere?
a canopy of starslike an astronomical painting on a heavenly ceiling.
what is a rotation?
it constitutes as the earth's rotation
what is the north celestial pole?
the point at which earth's axis intersects at Northern Hemisphere
what is the south celestial pole?
the point at which earth's axis intersects of at south celestial sphere
what is the celestial equator?
the intersection of the earth's equalateral plane
what are celestial coordinates?
latitude and longitude of celestial sphere
what is declination?
the latitude of CS
What is right acension?
the longitude of CS
What is a solar day?
day followed by sun
what is a diurnal motion
daily progress of sun and stars across sky
what is a sidereal day?
a day measured by the stars
what is an ecliptic?
apparent motion of sun on the sky traces the path of celestial sphere
what is the zodiac?
the constellations the sun passes, astrologists used this.
what is summer solstic?
the point at which the sun is at its northernmost point
what is winter solstice?
the point at which sun is at its most southern point
what are seasons?
marked difference between temperature of hot and cold season
what are equinoxes?
day when nighttime is equally the same length of time as daytime
what is an autmnal equinox?
when the sun crosses from the northern to the southern celestial hemisphere
what is a vernal equinox?
occurs in the spring, whjen the sun crosses the celstial equator moving north
what is a sidereal year?
time for the earth to orbit around the sun once
what is a precession?
the change in direction of earth's axis over time
what are phases?
changes in the moon
what does the new moon look like?
it is not visible
when does the quarter moon occur?
1 week into phase
what is the moon sidereal month?
27.3 days around earth
what is a syondic month?
month for moon to complete all its phases in 29.5 days
what is a lunar eclipse?
when earth covers the moon
what is a partial?
only a little
what is a total eclipse?
fully covering moon
what is an umbra?
the central region of the eclipse, the shadow
what is the penumbra?
some of the sun's light
what is the annular eclipse
when the moon covers the son
what is a baseline?
the baseline of a trianglatioj
what is triangulation?
finding distance of things through method of a triangl, invented by Euclid
what is a cosmic distance scale?
scale made up from triangulation
what is a parallax?
displacement between foreground object relative to background
what is a theory?
a framework of idease used to explain some set of the world
what is retrograde?
backwards motion of planets?
what is geocentric?
earth lay at center of universe
what is a epicycle?
cycle of indiviual planet's with Aristole's view of the universe's orbit
what is a deferent?
orbit in which planets followed within geocentric veiw
what is the ptolemaic model?
model of the stars as based on Greek astronomer Claudis Ptolemeause, who believed that tehre were more than 80 celestial beings orbiting the earth
what is helocentric mean?
sun centered
what is the copernican revolution?
the critical realization that a 16th century Polish cleric, Nicolas Copernicus, had once rediscovered the writing of Aristarchus regarding the heliocentricmodel
wwhat is an ellipse
a flattened circle
what is a focus?
a point in a ellipse
what is eccentricity?
distance between foci/length major axis
what is perhelion?
its point of closer approach to the sun
what is aphelion?
greatest distance from the sun
What is Kepler's second law?
an imaginary line connecting the sun to any planet sweeps out equal areas of the elli0pse in equal intervals of time.
What is a period?
defined as time needed for one planet to complete a one circuit around the sun
what is Kepler's third law?
the square of a planet's orbital period is preportional to the cube of its semi-major axis (P^2=a^3)
what is astronomical unit?
a unit custom made for the vast distance encountered in astronomy
what does radar stand for?
radio detection and ranging
what is newtonian mechanics
newton's theories
what is interia?
tendency of an object to keep moving at the same speed and in the same direction unless acted upon by a force
what is acceleration?
rate of change in velocity
what is the center of mass?
the "average" position of thematter comprisinig of two bodies
At the vernal equinox there are 12 hours of light and 12 hours of night _________ in the world.
when is the earth's vernal equinox?
march 20th
During a total eclipse of the moon, why isn't it dark?
its due to infraction
what is refraction?
whaen light slips by earth onto the moon, light passses curve of earth.
where is it always light at
on the south pole
where is it always dark?
on the north pole
when did Ptolemy exist, and what did he do?
Ptolemy-87-150-Catholic church was trying very hard to keep calender
what did Aristole believe?
that orbits had to be in circles because everything had to be natural, a circle was the most natural path
when did Copernicus live?
What was wrong with Copernicus's heliocentric path
made planets move in circles, but thhey move on epicenters
who was tycho brahe, when did he live, and what did he do?
king of denmark gave him an island to do observations at. Got into a duel once, so he had a fabricated nose.
How long was Tycho out on his island?
twenty years
how much of the gross domestic national product was spent on Tycho's island?
5% of Dutch GNP
What was funny about Brahe having his own island?
he had no telescope!
Who invented the telescope?
Who was Kepler?
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.
Who was born the year Galileo died?
At what month in the year is earth the closest?
the farthest?
Netwon's first law?
velocity is constant
when you don't have acceleration, your velocity is
Next force of an airplane traveling straight at 500 mph is what?
what are the basic forces in nature, and who many are there?

(1) gravity
(2) strong force
(3) electric
(4) weak
who invented calculus?
who influenced newton?
if something falls without air, how far would somehting fall in one second (including feathers)?
10 meters/second
What is responsible for keeping you on surface of earth?
attraction between you and earth's mass
when objects travel in circles, there must be a force on the object toward:
the center of the circle
F= G m m
what does the speed of a sattlite depend on?
the mass of the earth
What laws are more basic? newton or keplers?