Astronomy Quiz 3

In the heliocentric model, retrograde motion occurs when:

Earth catches and passes another planet in its orbit.

Which of the following observations provided the most direct challenge to the geocentric model of solar system orbits?

Phases of Venus

An object travels at 10 m/s through interstellar space. If no forces act upon it, it will:

Continue with the same velocity

Why do astronauts feel "weightless" inside the International Space Station?

They follow the same orbit as the space station.

Which of the following was NOT a reason the geocentric worldview was so popular in Europe in 1400 CE?

The geocentric model had been continuously improved by European astronomers over the previous millennium.

How would the strength of the force between the Moon and Earth change if the mass of the Earth were made two times greater than its current mass?

The force would double

Kepler's laws

(1) All planets move about the Sun in elliptical orbits, having the Sun as one of the foci. (2) A radius vector joining any planet to the Sun sweeps out equal areas in equal lengths of time. (3) The squares of the sidereal periods (of revolution) of the planets are directly proportional to the cubes of their mean distances from the Sun.