Chapter 13

Why was it necessary for Herschel to observe Uranus on more than a single night for him to be convinced that he had discovered a new object within our solar system?

What was the reason that, after the discovery of Uranus, astronomers began to believe that there was a planet beyond Uranus?

The discovery of Neptune is usually attributed to Urbain Leverrier. What did he do to warrant this recognition?

Why is it sometimes said that the discovery of Pluto near the position predicted by Percival Lowell was a lucky accident?

In what ways are Uranus and Neptune similar and in what ways are they different?

Describe why the pattern of sunlight and darkness for a hypothetical inhabitant of Uranus's polar regions has little relationship to the rotational period of Uranus.

What may be the reason that Uranus sometimes lacks the cloud fearures found on Neptune?

How does the appearance of the rings of Uranus compare with the appearance of the rings of Saturn?

What is the reason that some of the predicted occultations of stars by Neptune's rings could not be detected from the Earth?

Why is it sometimes incorrect to say that Pluto is farther from the Sun than is Neptune?

What arguments can be used to refute the proposition that Pluto is an escaped satellite of Neptune?

Describe the different ways in which searches for solar system planets beyond Pluto have been carried out. What were the results of those searches?

How do dwarf planets differ from planets?