astronomy chapter 3 pearson

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 shadow cast by a simple stick or obelisk allowed ancient people to

tell the time of day

On (Figure 1), you can see Kepler's third law (p^2=a^3) from the fact that __________.

the data falls on a straight line

Kepler's third law is often stated as p^2=a^3. The value a^3 for a planet is shown on __________.

the horizontal axis of figure 1

An original observation of Galileo's that helped to overturn the ancient Earth-centered model was

the phases of venus

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 compares to their orbits.

Galileo's contribution to astronomy included:

making observations and conducting experiments that dispelled scientific objections to the Sun-centered model.

The Moon takes roughly 28 days to complete one orbit around Earth. If the orbital radius of the Moon were twice its actual value, its orbital period would be

more than 56 days

When would you expect to see Venus high in the sky at midnight?

never

Two planets are observed going around a star. Planet Xoron has an orbital period that is twice as long as planet Krypton. Which planet has a shorter average orbital radius?

planet krypton

All of the following statements are true. Which one can be explained by Kepler's third law?

venus orbits the sun at a faster orbital speed than earth.

Uranus, not shown on the graph, orbits about 19 AU from the Sun. Based on the graph, its approximate orbital speed is between about __________.

5-10 km/s

Earth is closer to the Sun in January than in July. Therefore, in accord with Kepler's second law:

Earth travels faster in its orbit around the Sun in January than in July.

According to Kepler's third law:

Jupiter orbits the Sun at a faster speed than Saturn.

As a comet orbits around the Sun, its maximum speed is twice its minimum speed. What can we say about its orbit?

The comet is twice as far from the Sun at aphelion as at perihelion.

In the Greek geocentric model, the retrograde motion of a planet occurs when:

The planet actually goes backward in its orbit around Earth.

Which of the following orbits has the largest semimajor axis?

The semimajor axis is half of the distance across the ellipse in its longest direction (which means half of the major axis), which is also the planet's average distance from the Sun. Therefore, the ellipse that measures the longest across is the one with the largest semimajor axis.

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

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?

1) earth is slightly closer to the sun on one side of its orbit than on the other side. 2) the sun is located slightly off-centered from the middle of each planet's orbit.

Which of the following are the three key hallmarks of science?

1) models must make testable predictions that will force us to revise or abandon the model if they do not agree w/ observations. 2) modern science seeks explanations for observed phenomena that rely solely on natural causes. 3) science progresses through the creation and testing of models of nature that explain the observations as simply as possible.

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 p^2=a^3. Which of the following statements describe a characteristic of the solar system that is explained by Kepler's third law?

1) venus orbits the sun faster than earth orbits the sun. 2) inner planets orbit the sun at higher speed than outer planets.

How far does the planet in part F orbit from the Sun?

10 AU

Suppose (Figure 1) showed a planet on the red line directly above a value of 1000 AU^3 along the horizontal axis. On the vertical axis, this planet would be at __________.

1000 years^2

When Einstein's theory of gravity (general relativity) gained acceptance, it demonstrated that Newton's theory had been

incomplete

If an astronomer claims to have discovered an object with a very eccentric orbit, which of the following best describes the orbital trajectory of the object?

it looks like a very squased oval.

Why wasn't the Sun-centered model of Copernicus immediately adopted after he proposed it?

it was more noticeably more accurate than the old ptolemaic model

A planet is discovered orbiting the star 51 Peg with a period of four days (0.01 years). 51 Peg has the same mass as the Sun. Mercury's orbital period is 0.24 years, and Venus's is 0.62 years. The average orbital radius of this planet is

less than Mercury's

Which of the following is not true about a scientific theory?

A theory is essentially an educated guess.

Why do the planets orbit the Sun (i.e. why don't they crash into the Sun)?

Although the planets experience a force of gravity from the Sun, since they are moving, their trajectories bend around the Sun rather than lead directly into the Sun.

Which of the following orbits shows the planet at aphelion?

Aphelion is the point in a planet's orbit that is farthest from the Sun.

Which of the following orbits is the most eccentric?

Eccentricity is a measure of how "stretched out" an ellipse is. A perfect circle has zero eccentricity, and the most stretched out ellipse has the largest eccentricity.

Which of the following was not a major advantage of Copernicus's Sun-centered model over the Ptolemaic model?

It made significantly better predictions of planetary positions in our sky.

Which of the following paths could not be a real orbit for a planet around the Sun?

Kepler's first law tells us that the orbit of a planet must be an ellipse with the Sun at one focus. Therefore, the path that shows the Sun in the center of the ellipse, rather than at a focus, cannot be the real orbital path of a planet. (Note that the circular path is allowed because a circle is an ellipse in which both foci are at the center.)

Approximately how fast is Jupiter orbiting the Sun?

a little less than 15 km/s

An asteroid with an average orbital distance of 2 AU will orbit the Sun at an average speed that is __________.

a little slower than the orbital speed of mars

Suppose two comets, comet A and comet B, were orbiting the Sun, having the same average orbital radii. If comet A had a higher eccentricity than comet B, which comet would, during some portion of its orbit, have the highest orbital speed?

comet A

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.

In Ptolemy's Earth-centered model for the solar system, 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.

If Earth's orbit were very eccentric, but the average distance from the Sun were still 1 AU, its orbital period

would still be one year