chapter 13

Which of the following is true?

The deeper you dive into the atmospheres of the outer planets, the higher the temperature.

After the discovery of Uranus, astronomers calculated its orbit and predicted its position in the sky using Kepler's laws of planetary motion, which had been known since the early 17th century. However, they soon discovered a small discrepancy between the predicted and actual positions of Uranus. As a scientist, what should you do when presented with such a conflict between prediction and observation?

verify that your observations are correct think about what else might cause the observed discrepancy consider whether Kepler's laws need to be modified to account for the new observations consider that Uranus may not be a planet

Which statement about the magnetic fields of Uranus and Neptune is FALSE?

Both pass directly through the cores of their planets, like all other fields.

Starting with the hypothesis that a planet near Uranus was the cause of the orbital discrepancy, scientists had to develop a plan to find the unidentified planet. They started with what they knew about the discrepancies in the orbit of Uranus. Rank the steps in the order that scientists would take to discover the planet.

Calculate the mass, orbit,and likely position of the unidentified planet. Use optical telescope to search a region of the sky where the unidentified planet is predicted to be. Compare current observations to existing star charts to locate any new objects. Make continued observations to determine if the new object changes position relative to background stars.

One explanation that accounts for both Neptune's blue color and its warmer temperature is:

Neptune has a higher concentration of methane gas in its atmosphere.

Many scientific discoveries are made by chance. While studying one phenomenon, a scientist may discover a different one. Such was the case when William Herschel discovered the planet Uranus in 1781. Herschel was charting faint stars in the sky, when he discovered something that was not a star. How can astronomers tell the difference between a star and a planet? The following diagram depicts the sky as it would have appeared to Herschel when he first observed Uranus in 1781, as well as the same part of the sky over the next several nights. Label the indicated objects as stars or planets.

The diagrams illustrate how Herschel observed the same portion of night sky over several consecutive nights. He observed an object dim enough to be a star, but unlike the stars in the background, this object's position changed from night to night. It moved too slowly to be a nearby comet. Therefore, the object must, instead, be a large body orbiting the Sun quite distant from Earth. Quite accidentally, he had discovered a new planet, which was later named Uranus.

What could explain the darker appearance of moons and rings in the outer solar system?

They are made of small, sooty particles and radiation darkening with loss of volatile bright ices.

The magnetic fields in all planets are generated by the dynamo effect, caused by rapidly rotating and conducting material flowing in the interiors of the planets. We have just seen that all four of the jovian planets have magnetic fields. Earth also has a planetary magnetic field, but Venus does not, although it is very similar to Earth in mass. Which of the following would be a reason why Venus does not have a magnetic field?

Venus's very slow rotation rate does not allow a magnetic field to form.

The planet Uranus is:

barely visible with the naked eye

Bands in Uranus' atmosphere, similar to those seen on the other jovian planets,

form due to Uranus' rapid rotation.

Uranus and Neptune are like the other Jovian planets because they:

have rings

The most massive planet in the solar system is

jupiter

The following images show four planets in our solar system. Rank these planets from left to right based on the number of moons that orbit them, from highest to lowest. (Not to scale.)

jupiter,mars,earth, mercury

The following images show five planets in our solar system. Rank these planets from left to right based on their average surface (or cloud-top) temperature, from highest to lowest. (Not to scale.)

mercury,earth,mars, jupiter, neptune

Uranus' large axial tilt is thought to be the result of:

multiple catastrophic events, such as glancing collisions.

The farthest major planet from the Sun is

neptune

The following images show five planets in our solar system. Rank these planets from left to right based on the amount of time it takes them to orbit the Sun, from longest to shortest. (Not to scale.)

neptune,jupiter,mars,earth,mercury

In addition to Saturn's Titan, which other moon has a nitrogen atmosphere?

neptunes triton

The masses of Neptune and Uranus were first determined by:

observations of the motions of their satellites.

Our most detailed knowledge of Uranus and Neptune comes from:

spacecraft exploration

The unique feature of Neptune is:

that its atmosphere rotates more slowly than its interior.