Chapter 03 Homework Questions

For Professor Koch's Classes

1.   How did Eratosthenes estimate the size of the earth in 240 B.C.?

  1. by observing the duration of a solar eclipse

  2. by measuring the size of the earth's shadow on the Moon in a lunar eclipse

  3. by comparing the maximum altitude of the Sun in two cities at different latitudes

  4. by sending fleets of ships around the earth

  5. We don't know how he did it since all his writings were destroyed.

2.   Ptolemy was important in the history of astronomy because he

  1. developed a model of the solar system that made sufficiently accurate predictions of planetary positions to remain in use for many centuries.

  2. developed the first scientific model of the universe.

  3. was the first to believe in an Earth-centered universe.

  4. was the first to create a model of the solar system that placed the Sun rather than the earth at the center.

  5. was the first to believe that all orbits are perfect circles.

3.   Which of the following is not true of Hipparchus?

  1. He has been called the greatest astronomer in the Ancient World.

  2. He possessed trig tables and made many contributions to mathematics.

  3. He developed a geocentric model of the Universe in which retrograde motion of planets were explained using epicycles.

  4. He was the first to discover that planets move with respect to the "fixed" stars.

  5. He is often credited with being the first to successfully predict eclipses.

4.   The controversial book of this famous person, published in 1543 (the year of his death), suggested that the earth and other planets orbit the Sun.

  1. Tycho Brahe

  2. Copernicus

  3. Kepler

  4. Galileo

  5. Ptolemy

5.   When Copernicus first created his Sun-centered model of the universe, it did not lead to substantially better predictions of planetary positions than the Ptolemaic model. Why not?

  1. Copernicus misjudged the distances between the planets.

  2. Copernicus misjudged the speeds at which the planets orbit the Sun.

  3. Copernicus placed the planets in the wrong order going outward from the Sun.

  4. Copernicus placed the Sun at the center but did not realize that the Moon orbits the earth.

  5. Copernicus used perfect circles for the orbits of the planets.

6.   He discovered that the orbits of planets are ellipses.

  1. Tycho Brahe

  2. Copernicus

  3. Kepler

  4. Galileo

  5. Ptolemy

7.   Which of the following was not and observation by Galileo in support of the Copernican system?

  1. craters on the Moon

  2. stellar parallax

  3. sunspots

  4. Jupiter's moons

  5. phases of Venus

8.    Which of the following is not one of, nor follows directly from, Kepler's laws?

  1. The orbit of each planet about the Sun is an ellipse with the Sun at one focus.

  2. As a planet moves around its orbit, it sweeps out equal areas in equal times.

  3. The force of attraction between any two objects decreases with the square of the distance between their centers.

  4. A planet travels faster when it is nearer to the Sun and slower when it is farther from the Sun.

  5. More distant planets move at slower speeds.

9.    Kepler's second law, which states that as a planet moves around its orbit it sweeps out equal areas in equal times, means that

  1. a planet travels faster when it is nearer to the Sun and slower when it is farther from the Sun.

  2. a planet's period does not depend on the eccentricity of its orbit.

  3. planets that are farther from the Sun move at slower average speeds than nearer planets.

  4. the period of a planet does not depend on its mass.

  5. planets have circular orbits.

10. Which of the following statements about scientific theories is not true?

  1. A theory cannot be taken seriously by scientists if it contradicts other theories developed by scientists over the past several hundred years.

  2. A theory is a model designed to explain a number of observed facts.

  3. If even a single new fact is discovered that contradicts what we expect according to a particular theory, then the theory must be revised or discarded.

  4. A theory must make predictions that can be checked by observation or experiment.

  5. A theory can never be proved beyond all doubt; we can only hope to collect more and more evidence that might support it.

11. Use Kepler's Third Law to answer the following. If a planet were located 100AU from the Sun, what would its orbital period be?

  1. 100 years

  2. 1,000 years

  3. 10,000 years

  4. 1,000,000 years