intro to and history of astronomy

a star is 230 light years away. the light we see tonight from that star left it

230 years ago

a large body in space that consistently makes its own light (instead of merely reflecting another body's light) is called

a star

the way scientist know that a hypothesis in astronomy is a reasonable description of nature is to

do experiments and observations about the predictions of the hypothesis

even with the best and largest telescopes, we can't see all the stars in the milky way galaxy, even though these same telescopes can show us other galaxies. why is that?

dust in the space between stars builds up over large distances and blocks the light of stars behind the dustier parts of the milky way

when it comes to our place in the solar system today, which model do we accept?

heliocentric

according to the geocentric view, everything in the heavens had to go around the earth, which was the center of the universe. what objects did galileo discover with his telescope that clearly didn't go around the earth?

moons around the planet jupiter

when a planet temporarily moves westward in the sky over the course of several weeks or months (instead eastward, as it typically does) we call it:

retrograde motion

the astronomical unit (AU) as defined by astronomers is

the average distance between the earth and the sun

a light year is

the distance that light travels in one year

the natural object (not one that humans built) in space that's closest to earth is

the moon

the celestial sphere turns once around each day because

the planet on which we live is rotating

in ptolemy's system the planets orbit the earth and not the sun. how did the system explain the retrograde motion of the planets like jupiter?

the planets moved on a small circle whose center, in turn, circled a point near the earth

the star that provides energy for life on earth is

the sun

which of the following is NOT an argument for showing that the earth must be round:

the sun is seen blocking different constellations in the course of a year

in what fundamental way did the work of Galileo differ from his predecessors who had thought about the sky?

galileo used instruments and experiments to show him what nature was doing, instead of relying on pure logic