Who wrote down the equation for the law of gravitation?

Which of the following most accurately describes the shape of Earth’s orbit around the Sun?

Of the following planets, which takes the longest time to orbit the Sun?

What is a Sun-centered model of the solar system called?

How long does it take Earth to complete a sidereal orbit of the Sun?

How did Copernicus explain the retrograde motions of the planets?

Which planets can never be seen at opposition? Which planets never pass through inferior conjunction?

At what configuration (superior conjunction, greatest eastern elongation, etc.) would it be best to observe Mercury or Venus with an Earth-based telescope? At what configuration would it be best to observe Mars, Jupiter, or Saturn? Explain your answers.

What are the synodic and sidereal periods of a planet?

What are Kepler’s three laws? Why are they important?

In what ways did the astronomical observations of Galileo support a heliocentric cosmology?

How did Newton’s approach to understanding planetary motions differ from that of his predecessors?

What is the difference between mass and weight?

Why was the discovery of Neptune a major confirmation of Newton’s universal law of gravitation?

Why does an astronaut have to exert a force on a weightless object to move it?

A comet coming inward from the Kuiper belt, a region of Sun-orbiting debris out beyond the orbit of Neptune, experiences a gravitational force from the Sun. Does the presence of the planets affect the comet’s orbit? Explain your reasoning.

How would the weight of an astronaut on the Moon compare to her weight on Earth?

How would the mass of an astronaut on the Moon compare to his mass on Earth?

An astronomer observes a new comet and calculates that it will exit the solar system and not return. Which of the following best describes the path of the comet?

From the definition KE = ½mv², derive the equation KE = p²/2m, as discussed in Appendix P.

Is it possible for an object in the solar system to have a synodic period of exactly 1 year? Explain your answer.

Describe why there is a systematic decrease in the synodic periods of the planets from Mars outward, as shown in Table 2-1.

Make diagrams of Jupiter’s phases as seen from Earth and as seen from Saturn.

In what direction (left or right, eastward or westward) across the celestial sphere do the planets normally appear to move as seen from Australia? In what direction is retrograde motion as seen from there?

The dictionary defines astrology as “the study that assumes and attempts to interpret the influence of the heavenly bodies on human affairs.” Based on what you know about scientific theory, is astrology a science? Why or why not? Feel free to further explore astrology, if you wish, before answering this question.

Which planet would you expect to exhibit the greatest variation in apparent brightness as seen from Earth? Explain your answer.

Use two thumbtacks (or pieces of tape), a loop of string, and a pencil to draw several ellipses. Describe how the shapes of the ellipses vary as you change the distance between the thumbtacks.