Explorations: An Introduction to Astronomy (Arny), 7th Edition

Chapter 9: The Terrestrial Planets

Problems

1
Calculate the escape velocity needed to launch a rocket from the surface of Mercury.
2
Venus rotates (spins) clockwise while orbiting the Sun counterclockwise. Draw a diagram to show how, for a "retrograde" planet like Venus, the time from solar noon to solar noon is shorter than the time required to spin 360 degrees (the opposite is true for Earth—see Essay3/Fig. E3.2). Try using a rotation period of about half of the orbital period.
3
How long would it take to send a radio signal to a spacecraft at Venus when Venus is at opposition?
4
Earth's atmospheric pressure drops by about a factor of 2 every 5 km higher up you go, so it is one-fourth the surface pressure at 10 km, for example. How high up in Earth's atmosphere would you have to go to reach a pressure similar to the 0.6% atmospheric pressure on Mars? (You can do this mathematically with logarithms or plot the changing pressure with elevation and estimate the height where this pressure is reached.)
5
Olympus Mons is 26 kilometers above the surrounding surface of Mars. Calculate the surface gravity on Mars at the surface and on top of Olympus Mons (neglecting any effects on gravity from the mountain itself). What percentage of the surface value is the difference in the acceleration of gravity?
6
In chapter 13, we will learn that the brightness of light decreases in proportion to the square of the distance from the source. We know sunlight plays an important role in the conditions on the planets and also is used to power equipment like the Mars rovers. How many times brighter is sunlight at Venus's distance from the Sun than at Earth? How many times dimmer is it at Mars than at Earth? (Distances from the Sun compared to Earth's can be found in table 9.1 or in the appendix.)
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