Back to Assignments

A100 -- Dan Swearingen Homework 7
The Last Homework (if you don't count the final)
Due Tuesday, December 3 by the beginning of class

Page 311, Questions For Review:

6. Why must the interior of the Sun be so hot?

17. What is meant by solar neutrinos? Why do astronomers say there is a discrepancy? Why is the discrepancy of interest?

Page 312, Thought Questions:

3. In this problem you will calculate approximately the temperature of the Sun's core. You can do it either step by step, or by writing out all the algebra to obtain a final result. You will need the following ideas:

(a) The pressure in a gas is given by the ideal gas law .

(b) The density is a body's mass per volume, which for a sphere is .

(c) The pressure force from the interior is P x A, where A is the area over which the pressure acts. You can take that as the sun's cross-section, . Thus the pressure force is .

Finally, you need to invoke hydrostatic equalibrium: "Pressure forces must balance gravitational forces." Approximate the gravitational force holding the Sun together by assuming it is split into two equal halves and apply Newton's law of gravity to calculate the force between the halves. Assume they are separated by one solar radius.

Go to the website:

this is an archive of NASA's Astronomy Picture of the Day website at

At the archive, find a page of the day which interests you and write a half page description (in your own words) of its topic and some of the resources linked to that page.

Places to access the web: Here on campus at the various computer labs, from home with your PC and AOL or connection to school, and the Monroe County Library has public web terminals.

Ice at the Lunar South Pole (December 4, 1996)

Credit: Clementine, BMDO, NRL, LLNL

Explanation: Ice on the Moon? The prospecting Clementine spacecraft may well have discovered it. In 1994, Clementine spent 70 days in lunar orbit mapping the Moon's surface.

Like I said in class: I'm really excited about the discovery of quantities of ice on the moon. However, I wonder why this was a DoD mission?

Back to Assignments