Astronomy Ch 3 hw
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?
The planets are all much too large compared to their orbits.
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?
Venus on upper left corner
According to Kepler's second law, Jupiter will be traveling most slowly around the Sun's ______.
aphelion
Earth is slightly closer to the Sun in January than in July. How does the area swept out by Earth's orbit around the Sun during the 31 days of January compare to the area swept out during the 31 days of July?
both areas are the same
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
brightest // midnight
The great contribution of Nicholas Copernicus was to..
create a detailed model of our solar system with the Sun rather than the Earth at the center
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.
eastward// westward
The extent to which Mar's orbit differs from a perfect circle is ______.
eccentricity
Earth orbits in the shape of a/an ______ around the sun.
ellipse
Earth is located at one ______ of the Moon's orbit.
focus
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?
gibbous (nearly full)
Why wasn't the Sun-centered model of Copernicus immediately adopted after he proposed it?
it was not noticeably more accurate than the old Ptolemaic model
Galileo's contribution to astronomy included:
making observations and conducting experiments that dispelled scientific objections to the Sun-centered model.
The great contribution of Tycho Brahe was to _________.
observe planetary positions with sufficient accuracy so that Kepler could later use the data to discover the laws of planetary motion
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
perihelion
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
position among constellations//several months
The mathematical form of Kepler's third law measures the period in years and the ______ in astronomical units (AU).
semimajor axis
The shadow cast by a simple stick or obelisk allowed ancient people to
tell the time of day
An original observation of Galileo's that helped to overturn the ancient Earth-centered model was
the phases of Venus
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.
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 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.
Which of the following are the three key hallmarks of science?
-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.
Which of the following can you observe about Venus with the naked eye? Select all that apply.
1. Venus sometimes shines brightly in the western sky shortly after sunset 2. Venus sometimes shines brightly in the eastern sky shortly before dawn
What is really happening in space during the periods when we see Mars going through apparent retrograde motion?
Earth is passing by Mars in its orbit around the Sun.
What practical value did astronomy offer to ancient civilizations?
It helped them keep track of time and seasons, and it was used by some cultures for navigation.
All of the following statements are true. Which one can be explained by Kepler's second law?
Mars moves faster in its orbit when it is closer to the Sun than when it is farther from the Sun.
In Ptolemy's Earth-centered model, when would Venus appear directly behind the Sun as viewed from Earth?
Never
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.
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?
Pluto moves faster when it is closer to the Sun than when it is farther from the Sun.
