General Astronomy, 29:61
Fall, 2005
First Homework Set...August 26, 2005. Due September 2, 2005

Show calculations and give reasons for your answers. Don't go around confused and despondent; if you do not know how to get started, ask us for help. The purpose of problem sets is to promote thinking and lead to understanding, not produce a confiteor of revealed truth.

(1) The surface gravity on Mars is 0.381 times that on Earth, and its atmosphere is nearly entirely CO$_2$. Assuming a surface temperature of 260K, calculate the atmospheric pressure scale height on Mars.

(2) Here in Iowa, the ecliptic crosses the meridian at a maximum altitude angle of $72^{\circ}.1$, and a minimum altitude angle of $24^{\circ}.9$. The inclination of the Moon's orbit is $5^{\circ}.1$. What is the highest altitude angle that the Moon can appear here in Iowa? What is the lowest altitude angle at which it will transit (i.e. cross the meridian)?

(3) Estimate the summer-winter difference in the atmospheric pressure scale height on Earth.

(4) Use the JPL solar system simulator (on the course home page) to find the current distance to the planet Saturn. If you transmit a command to the Cassini spacecraft, how long must you wait to receive confirmation that it carried out the command?

(5) You are on a commercial airliner and the altimeter stops functioning. The crew and all the passengers are in a panic. However, some of the aircraft instruments are still functioning and their data is visible on the entertainment center. You see that the pressure outside is $3.1 \times 10^4$ Newtons/m$^2$. You do a quick calculation on an air-sickness bag and figure out the altitude of the aircraft. What is it?

(6) Use the JPL Solar System Simulator to answer the following questions. (a) In what part of the sky, and at what time of day, would you see the planet Mercury? (b) What about Saturn? Hint: In using the Solar System Simulator, choose ``The Solar System'' in the ``show me'' box, choose ``above'' for ``as seen from'', and for ``Field of View'', choose ``I want a field view of ...''. You should make an intelligent choice for the size of the field.