Under what circumstances can differentiation occur in a planet?
The planet must have a molten interior.
Which of the following is not a characteristic of the inner planets?
They all have substantial atmospheres
Patterns of stars in constellations hardly ever change in appearance over times of even a few thousand years. Why?
The stars in our sky actually move rapidly relative to us... thousands of km per hour... but are so far away that it takes a long time for this motion to make a noticeable change in the patterns in the sky
What is the ecliptic plane?
the plane of earth's orbit around the sun
Which of the following statements about the celestial sphere is not true?
the "celestial sphere" is just another name for our universe
Which of the following statements about the celestial sphere is true at all latitudes?
it represents an extension of the earth's equator onto the celestial sphere
What is the ecliptic
the sun's apparent path along the celestial sphere
what is a circumpolar star?
a star that always remains above your horizon
Which of the following statements about circumpolar stars is true at all latitudes?
they always remain above your horizon.
we describe a position on earth's surface by stating its...
latitude and longitude
we describe a position on the celestial sphere's surface by stating its...
altitude and azimuth
by locating the ncp in the sky, how can you determine your latitude?
the altitude of the ncp is the same as your latitude
the point directly over your head is called
which of the following correctly describes the meridian in your sky?
a half-circle extending from your horizon due north, thru your zenith, to your horizon due south
which of the following best describes what we mean by the universe?
the sum total of all matter and energy
large, glowing ball of gas that generates heat and light thru nuclear fusion
an object that orbits a planet
a relatively small and icy object that orbits a star
a great island or star in space, all held together by gravity and orbiting a common center
ptolomey was important in the history of astronomy because he
developed a model of the solar system that made sufficiently accurate predictions of planetary positions to remain in use for many centuries.
how did the ptolemaic model explain the apparent retrograde motion of the planets
it held that the planets moved along small circles that moved on larger circles around earth
why did ptolemny have the planets orbiting earth "circles upon circles" in his model of the universe?
to explain the fact that planets sometimes appear to move westward, rather than eastward, relative to the stars in our sky
where was the sun in ptolemy's model of the universe?
between the orbits of venus and mars
he discovered that the orbits of planets are ellipses
he discovered that jupiter has moons:
when copernicus first created his sun-centered model of the universe, it did not lead to substantially better predictions of planetary positions than the ptolemaic model. Why not?
copernicus used perfect circles for the orbits of the planets
which of the following was not observed by galileo?
one of the nails in the coffin for earth-centered universe was
galileo's observations of the moons of jupiter
which of the following is not one of, nor follows directly from, kepler's laws?
the force of attraction between any two objects decreases with the square of the distance between their centers
kepler's third law, p2=a3, means that
planets that are farther from the sun move at slower average speeds than nearer planets
kepler's second law, which states that as a planet moves around its orbit it sweeps out equal areas in equal times, means that
a planet travels faster when it is nearer to the sun and slower when it is farther from the sun.
which of the following is an example in which you are traveling at constant speed but not a constant velocity
driving around in a circle at exactly 100 km/hr
if your mass is 60 kg on earth, then what would your mass be on the moon?
newton's second law of motion tells us that the net force applied to an object equals its
mass times acceleration
the movement of a pool ball after being struck by a cue is an example of
newton's second law of motion
absolute zero is
0 degrees kelvin
according to the universal law of gravitation, the force due to gravity is
inversely proportional to the square of the distance between objects
according to the universal law of gravitation, if you double the masses of both attracting objects, then the gravitational force between them will
increase by a factor of 4
the center of mass of a binary star system is
the point at which the two objects would balance if they were somehow connected
the frequency of a wave is
all of the above
the wavelength of a wave is
the distance between two adjacent peaks of the wave
how are the wavelength, frequency, and energy related for photons of light?
longer wavelength means lower frequency and lower energy
from shortest to longest wavelength, which of the following correctly orders the different categories of electromagnetic radiation
gamma rays, x rays, uv light, visible light, infrared, radio
which of the following statements about x rays and radio waves is not true?
x rays travel thru space faster than radio waves
we can see each other in the classroom right now because we
reflect visible light
without telescopes or other aid, we can look up and see the moon in the night sky because it
reflects visible light
visible light from a distant star can be spread into a spectrum by using a glass prism or
a diffraction grating
what do astronomers mean by light pollution?
light pollution refers to light used for human activities that brightens the sky and hinders astronomical observations.