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Planets Test#2
50 points total
Due at 5 PM on May 9, 2013.
You can use your notes and the book for this test and any other resource you can think of. You may also consult with others about the answers to questions. However, all answers, especially those where you have to write out explanations, should be in your own words. Any obvious similarities to the work of others will result in no points. Be careful about formulas - make sure you use the right units and constants for them. You should number and write your answers neatly on some other sheets of paper - and make sure you include your work so that I can at least give you partial credit where appropriate. If you need to use a constant, use those that are in the SI system – kg, meters, Joules, etc.
1. (6 points) The diameter of an impact crater depends upon the following features –
Density of the impactor (the object hitting the target)
Density of the target
Gravity of the target
Radius of the impactor
Angle of impact relative to vertical
Velocity of impactor
How does each affect the crater diameter? You can just say “if the density of the impactor is greater, then the size of the crater would be bigger/smaller” and so on. Assume that the impacts are occurring on a world without an atmosphere.
2. (6 points) Check out the image at the website. It is an outline of the large corona that is displayed near LAT 113. Show the location of various objects on the corona such as impact craters, flow features, fields of volcanoes and other identifiable structures. You might want to use a number or letter labeling system, such as “A= impact crater, B=flow feature”, etc. or color code the image with the features that you have identified. Only identify the features within the boundary of the corona (the white area in the image). Make sure you turn in your corona picture/map along with the labels/legend you have for it. You can not print out an image showing the features in the corona and just label them - you must use the image at the website or something similar (something that doesn’t show an actual image from NASA of the corona).
3. (6 points) Fill in the values for the Drake Equation and come up with your own personal value for it. For R*use a value of 10 stars/year, and for the rest of the values you need to provide their values and the reason behind the values you chose (you can just go with your gut instincts on some of them).
5. (6 points) If you were actually on Olympus Mons (the really big mountain on Mars), you are experiencing an atmosphere that is rich in CO2, and one that has a pretty low pressure compared to what is at “sea level” on Mars (so the value POlympus Mons/PSea levelis very small). The molecular weight of CO2 is 44 AMU. If the atmosphere were changed so that it contained mainly N2 (molecular weight = 28 AMU), how would that effect the ratio of the air pressure on the mountain to what is experienced at “sea level” (POlympus Mons/PSea level)? In other words how much would the value of POlympus Mons/PSea levelchange when you go from a CO2 rich atmosphere to one that is N2 rich? Assume that the temperature always equals 215 K, g=3.71 m/s2, 1 AMU = 1.66 x 10-27 kg, and the top of Olympus is 21,000 meters above martian “sea level”.
Evil question #4. (14 points) A star (with a mass=1.3 x Sun’s mass) is observed to undergo a velocity change due to the presence of a planet around it. The period of the orbit is 3.312 days, and the eccentricity of the orbit is 0 (=e).
a. Use the amplitude relation from the notes (amplitude = ½ full variation) to determine the mass of the planet. For simplicity assume that the inclination (i) is 10º. You’ll want to make sure you have everything in the proper units.
b. The star that the planet orbits has a luminosity of about 3.4 x Sun’s luminosity. How large is the habitable zone for this star? Determine the inner and outer limits.
c. Is the planet within this star’s habitable zone?
d. By chance the planet also transits the star, so astronomers are able to determine the radius of the planet. The star has a radius that is 1.23 x Sun’s radius and planet has a radius that is 0.0772 that of the star. What is the radius of the planet in meters?
e. What is the average density of the planet?
6. (8 points) Use equation 5-2 (estimate of central pressure) to calculate the central pressure of the following –
a. Earth
b. Jupiter
c. Uranus
d. Pluto
7. (4 points) There are only intermediate sized craters on Venus. Why?