Middle Georgia State University

Course title: ASTR 1010K

Chapter 2 Homework

1)Who wrote down the equation for the law of gravitation?

2. How long does it take Earth to complete a sidereal orbit of the sun?

3. Which planets can never be seen at oppositions? Which planets never pass through inferior conjunction?

4. What are the synodic and sidereal periods of a planet?

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

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

7. Form the definition KE=1/2mc, derive the equation KE=p^/2m as discussed in AN Astronomer’s Toolbox 2-2.

8. Convert:

1. 8.3 pc (parsec) into light-years

2. 6.52 ly into parsecs

3. 8450 AU into kilometers

4. 2.7x10^3 Mpc into kiloparsecs

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

10. A line joining the Sun and an asteroid was fond to sweep out 5.2 square astronomical units of space in all of 2012. How much area was swept out of 2013? In the five years from 2008 to 2013?

11. A comet moves in a highly elongated orbit (e=0.95) around the sun, with a period of 1000 years. What is the length of the semimajor axis of the comet’s orbit? Referring to Figure 2-8b, estimate the comer’s orbit? Referring to Figure 2-8b, estimate the farthest distance that the comet can travel from the Sun.

12. The orbit of a spacecraft around that Sun has a perihelion distance of 0.5 AU and an aphelion distance of 3.5 AU. What is the spacecraft’s orbital period?