Chapter 3 Flashcards
questions from chapter 3
In Ptolemy’s Earth-centered model for the solar system, Venus’s phase is never full as viewed from Earth because it always lies between Earth and the Sun. In reality, as Galileo first recognized, Venus is __________.
full whenever it is on the opposite side of the Sun from Earth, although we cannot see the full Venus because it is close to the Sun in the sky
Imagine that Venus is in its full phase today. If we could see it, at what time would the full Venus be highest in the sky?
at noon
When would a new Venus be highest in the sky?
at noon
When would you expect to see Venus high in the sky at midnight?
never
In Ptolemy’s Earth-centered model for the solar system (not shown), Venus always stays close to the Sun in the sky and, because it always stays between Earth and the Sun, its phases range only between new and crescent. The following statements are all true and were all observed by Galileo. Which one provides evidence that Venus orbits the Sun and not Earth?
We sometimes see gibbous (nearly but not quite full) Venus
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?
Venus orbits the Sun faster than Earth orbits the Sun.
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.
All the planets orbit the Sun in nearly the same plane.
Inner planets orbit the Sun at higher speed than outer planets.
Pluto moves faster when it is closer to the Sun than when it is farther from the Sun.
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?
Pluto moves faster when it is closer to the Sun than when it is farther from the Sun.
The Sun is located slightly off-center from the middle of each planet’s orbit.
Venus orbits the Sun faster than Earth orbits the Sun.
Inner planets orbit the Sun at higher speed than outer planets.
All the planets orbit the Sun in nearly the same plane.
Earth is slightly closer to the Sun on one side of its orbit than on the other side.
Pluto moves faster when it is closer to the Sun than when it is farther from the Sun.
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 . Which of the following statements describe a characteristic of the solar system that is explained by Kepler’s third law?
The Sun is located slightly off-center from the middle of each planet’s orbit.
All the planets orbit the Sun in nearly the same plane.
Venus orbits the Sun faster than Earth orbits the Sun.
Pluto moves faster when it is closer to the Sun than when it is farther from the Sun.
Earth is slightly closer to the Sun on one side of its orbit than on the other side.
Inner planets orbit the Sun at higher speed than outer planets.
Venus orbits the Sun faster than Earth orbits the Sun.
Inner planets orbit the Sun at higher speed than outer planets.
Consider the hypothetical observation “a planet beyond Saturn rises in west, sets in east.” This observation is not consistent with a Sun-centered model, because in this model __________.
the rise and set of all objects depends only on Earth’s rotation
We never see a crescent Jupiter from Earth because Jupiter __________.
is farther than Earth from the SUN
Earth is located at one _________ of the moon’s orbit
focus
According to Kepler’s second law, Jupiter will be travelling most slowly around the sun at _____________.
aphelion
Earth orbit in the shape of an ___________ around the sun
ellipse
The mathematical form of Kepler’s third law measures the period in years and the _________ in astronomical units (AU).
semimajor axis
According to Kepler’s second law, Pluto will be travelling fastest around the sun when at __________.
perihelion
The extent to which Mars’ orbit differs from a perfect circle is called its ________.
eccentricity
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.
Scientific thinking is _________.
based on everyday ideas of observation and trial-and-error experiments
The names of the seven days of the week are based on _________.
the seven naked-eye objects that appear to move among the constellations
The Metonic cycle is
used to keep lunar calendars approximately synchronized with solar calendars.
Ptolemy was important in the history of astronomy because he _________.
developed a model of the solar system that made sufficiently accurate predictions of planetary positions to remain in use for many centuries
The ancient Greeks get a lot of attention for their contributions to science because _________.
they were the first people known to try to explain nature with models based on reason and mathematics, without resort to the supernatural
What do we mean by a geocentric model of the universe?
A model designed to explain what we see in the sky while having the Earth located in the center of the universe.
What was the Ptolemaic model?
An Earth-centered model of planetary motion published by Ptolemy
The great contribution of Nicholas Copernicus was to _________.
create a detailed model of our solar system with the Sun rather than Earth at the center
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
Which of the following was not observed by Galileo? Phases of Venus. Mountains and valleys on the Moon Stellar parallax Four moons orbiting Jupiter
Stellar paralax
Which of the following statements about an ellipse is not true?
An ellipse with a large eccentricity looks much more elongated (stretched out) than an ellipse with a small eccentricity. The semimajor axis of an ellipse is half the length of the longest line that you can draw across an ellipse. A circle is considered to be a special type of ellipse. The focus of an ellipse is always located precisely at the center of the ellipse.
The focus of an ellipse is always located precisely at the center of the ellipse.
Which of the following is not one of, nor a direct consequence of, Kepler’s Laws?
More distant planets orbit the Sun at slower speeds.
A planet or comet in a noncircular orbit travels faster when it is nearer to the Sun and slower when it is farther from the Sun.
As a planet moves around its orbit, it sweeps out equal areas in equal times.
The force of attraction between any two objects decreases with the square of the distance between their centers.
The orbit of each planet about the Sun is an ellipse with the Sun at one focus.
The force of attraction between any two objects decreases with the square of the distance between their centers.
Scientific models are used to _________.
make specific predictions that can be tested through observations or experiments
In science, a broad idea that has been repeatedly verified so as to give scientists great confidence that it represents reality is called _________.
a theory
