Exam 10: Our Barren Moon

Estimates of the heights of lunar mountains can be made by measuring the lengths of their shadows when the Sun angle on them is relatively low. If a shadow length on a photograph of an isolated mountain on a flat plain is measured at 5 km when the solar elevation angle (angle above the horizon as seen by someone on the Moon) is about 6°, what is the mountain height above the plain? (A diagram might help, and the small-angle formula in Chapter 1, Universe, 11th ed. will be useful.)

Suppose that two regions on the Moon have ages, respectively, of 3.7 and 4.3 billion years. Based on these ages, we expect to find that:

Earth's rotation is slowing down because of the tidal interaction between Earth and the Moon at a rate of 2 milliseconds per century. If this rate remains constant at the present value, how long will it take for 1 day on Earth to become 2 seconds longer than it is now?

If we think about two rocks of equal mass on the Moon, one on the near side and one on the far side, then we can think of the tidal force as the difference between the gravitational force by Earth on the near-side rock and the gravitational force by Earth on the far-side rock. How quickly does this tidal force decrease with increasing distance from Earth?

Earth has several lithospheric plates that gradually move in a process called plate tectonics. How many such plates are there on the Moon?

Libration is:

The number of meteoroids with masses between 100 g and 1000 kg (between that of a bag of sugar and that of an automobile!) that hit the Moon each year is:

Moonquakes occur:

Maria are:

What is the approximate age of the oldest rocks brought back from the Moon by astronauts during the Apollo program?

The Moon's appearance, when its whole surface is examined, could be described as:

The Moon apparently has:

Compared to earthquakes, moonquakes are:

How many human beings have walked on the Moon?

The Moon raises tides on Earth. Does Earth raise tides on the Moon?

Which of the following techniques is not used to gather information about the Moon's interior?

The impact craters on Earth are younger than a few million years old, whereas ages of lunar craters extend back billions of years. Why is this?

Considering two rocks of equal mass on the Moon, one on the near side and one on the far side, we can think of the tidal force as the difference between the gravitational force by Earth on the near-side rock and on the far-side rock. If the Moon were orbiting at 3 times its present distance from Earth, what would the tidal force be, compared to its present value?

What can be said to evaluate the fissure theory of the Moon's origin-the theory that Earth was spinning so rapidly in its semimolten state that a large piece flew out and cooled to become the Moon?

Why are the lunar maria concentrated almost entirely on the near side of the Moon?