Summarize the development of the Greek geocentric model through Ptolemy. How did the Ptolemaic model account for apparent retrograde motion?
The Ptolemiac model was able to explain retrograde motion by having the planets move on smaller circles attached to the larger circles on which they went around Earth.
-Science progresses through the creation and testing of models of nature that explain the observations as simply as possible.–Modern science seeks explanations for observed phenomena that rely solely on natural causes.—Models must make testable predictions that will force us to revise or abandon the model if they do not agree with observations.
At most times, Mars appears to move __________ relative to the stars. The exceptions are during its periods of apparent retrograde motion, when Mars appears to move __________ relative to the stars.
If you wanted to document the apparent retrograde motion of Mars, you would need to measure and record Mars”s…. over a period of_________ returned
What is really happening in space during the periods when we see Mars going through apparent retrograde motion?
Consider a time when Mars is in the middle of one of its periods of apparent retrograde motion. During this time, Mars appears _____ in our night sky and crosses the meridian around _____.brightest; midnight
The Sun-centered system pictured in the lower window of the video offers a simple explanation for observations of apparent retrograde motion. Should these facts alone have been enough to convince the ancient Greeks that Earth really does go around the Sun?
No, because the Greeks had an Earth centered model that also accounted for apparent retrograde motion.
observe planetary positions with sufficient accuracy so that Kepler could later use the data to discover the laws of planetary motion
making observations and conducting experiments that dispelled scientific objections to the Sun-centered model.
Based on the video, which Venus phase would be impossible to see (from Earth) if Venus orbited Earth as described in Ptolemy”s Earth-centered model?
1. Venus sometimes shines brightly in the western sky shortly after sunset2. Venus sometimes shines brightly in the eastern sky shortly before dawn
In Ptolemy”s Earth-centered model, when would Venus appear directly behind the Sun as viewed from Earth?
As you learned in the video, Galileo”s observations of Venus in gibbous (nearly full) phase showed conclusively that Venus orbits the Sun, not Earth. Which figure shows Venus”s position when Galileo saw it in gibbous phase?
The video states that the planetary orbits are shown to scale. Which statement correctly describes the way the planet sizes are shown compared to their orbits?
Kepler”s first law states that the orbit of each planet is an ellipse with the Sun at one focus. Which of the following statements describe a characteristic of the solar system that is explained by Kepler”s first law?
—The Sun is located slightly off-center from the middle of each planet”s orbit.–Earth is slightly closer to the Sun on one side of its orbit than on the other side.
Kepler”s second law states that as a planet orbits the Sun, it sweeps out equal areas in equal times. Which of the following statements describe a characteristic of the solar system that is explained by Kepler”s second law?
Kepler”s third law states that a planet”s orbital period, p, is related to its average (semimajor axis) orbital distance, a, according to the mathematical relationship p2=a3. Which of the following statements describe a characteristic of the solar system that is explained by Kepler”s third law?
–Inner planets orbit the Sun at higher speed than outer planets.–Venus orbits the Sun faster than Earth orbits the Sun.
The mathematical form of Kepler”s third law measures the period in years and the ______ in astronomical units (AU).
According to Kepler”s second law, Pluto will be traveling fastest around the Sun when at ______.The extent to which Mar”s orbit differs from a perfect circle is ______.eccentricity