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Pathways to Astronomy

Stephen E. Schneider

Chapter 47

Comets - all with Video Answers

Educators

Chapter Questions

02:37

Problem 1

Use Kepler's third law to find the semimajor axis of Halley's comet, given that its orbital period is 76 years.

Dading Chen
Dading Chen
Numerade Educator
03:05

Problem 2

With the result of problem 1 and the fact that for a very elliptical orbit the distance farthest from the Sun is roughly twice the semimajor axis, estimate how far from the Sun Halley's comet travels. What planet is about that same distance from the Sun? How does this distance compare with the distance to the Kuiper belt?

Sheryl Ezze
Sheryl Ezze
Numerade Educator
07:04

Problem 3

Use Kepler's third law to determine the period of a comet with an orbit extending from $1 \mathrm{AU}$ to $50,000 \mathrm{AU}.$

Linda Winkler
Linda Winkler
Numerade Educator
04:48

Problem 4

Use data from the text to estimate the total kinetic energy, in joules, of the impact of NASA's Deep Impact probe onto comet Tempel 1. If the comet has a mean diameter of about 6 $\mathrm{km}$ and a density of about $0.8 \mathrm{kg} / \mathrm{L}$, and is orbiting at about $30 \mathrm{km} / \mathrm{sec}$ what is its kinetic energy?

Andy Chen
Andy Chen
Numerade Educator
07:30

Problem 5

The temperature, $T$, of a body decreases as the square root of its distance, $d$, from the Sun increases: $T=\mathrm{constant} / \sqrt{d}$. If the temperature at $1 \mathrm{AU}$ is $250 \mathrm{K}$, estimate the temperature of a comet nucleus in the Oort cloud.

Daniel Azubuike
Daniel Azubuike
Numerade Educator
03:36

Problem 6

As a comet orbits the Sun, its temperature changes approximately as described in problem 5
a. Calculate the distance from the Sun at which it would reach the sublimation temperature of water (sublimates at $T=$ 180 K). Repeat for ammonia (130 K) and carbon dioxide $(80 \mathrm{K})$
b. Based on your results in (a), describe how a comet would behave as it orbits the Sun.
c. What would be the effect on the comet's temperature if it had dark regions on its surface? Qualitatively, how would this affect its behavior as it orbited the Sun? Explain your reasoning.

Donald Albin
Donald Albin
Numerade Educator