CH 1 – Space – Flashcards

In Ptolemy's geocentric model, retrograde motion occurs when the planet is closest to us, on the inside portion of the

According to Copernicus, retrograde motion for Venus must occur around

Which of these observations of Galileo refuted Ptolemy's epicycles?

The force of gravity varies with

A planet whose distance from the Sun is 3 A.U. would have an orbital period of how many Earth-years?

How much stronger is the gravitational pull of the Sun on Earth, at 1 AU, than it is on Saturn at 10 AU?

According to Newton's second law, if you double the force acting on a body, the acceleration will double.

According to Newton's first law, an object traveling in a circle does not have a force acting on it.

Kepler relied heavily on the telescopic observations of Galileo in developing his laws of planetary motion.

Kepler found the orbits of planets are ellipses, not circles.

A planet (or comet) will speed up as it approaches the Sun

Copernicus believed the Earth was the center of all celestial motion.

According to Copernicus, retrograde motion occurs at opposition for the outer planets.

In Ptolemy's geocentric model, the planet's motion along its deferent is all that is needed to understand retrograde motion.

The place in a planet's orbit that is closest to the Sun is called

geocentric

heliocentric

both geocentric and heliocentric

heliocentric advantage

geocentric advantage

both heliocentric and geocentric advantages

The geocentric model, in all of its complexity, survived scientific scrutiny for almost 1400 years. However, in modern astronomy, scientists seek to explain the natural and physical world we live in as simply as possible. The complexity of Ptolemy's model was an indicator that his theory was inherently flawed. Why, then, was the geocentric model the leading theory for such a long time, even though the heliocentric model more simply explained the observed motions and brightness of the planets?

Galileo Galilei was the first scientist to perform experiments in order to test his ideas. He was also the first astronomer to systematically observe the skies with a telescope. Galileo made four key observations that challenged the widely accepted philosophical beliefs on which the geocentric model was based, thus providing support for the heliocentric model. From the following list of observations, which are the key observations made by Galileo that challenged widespread philosophical beliefs about the solar system?

Johannes Kepler used decades of Tycho Brahe's observational data to formulate an accurate description of planetary motion. Kepler spent almost 30 years of his life trying to develop a simple description of planetary motion based on a heliocentric model that fit Tycho's data. What conclusion did Kepler eventually come to that revolutionized the heliocentric model of the solar system?

Astronomers have made many observations since the days of Galileo and Kepler to confirm that the Sun really is at the center of the solar system, and that the planets revolve around the Sun in elliptical orbits. Which observation(s) could you make today that Galileo and Kepler could not have made to confirm that the heliocentric model is correct?