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Astro 150 Midterm Short Answer

Terms in this set (16)

Explain why Earth, Mars & Venus different size cutoffs for the smallest impact craters.
Earth, Mars, and Venus have different size cutoffs because their atmospheres will only let certain objects of certain sizes through AKA earth has a thick atmosphere and will only let small impactors
What is the difference between weather and climate? Which of these relates more closely to global warming? Explain.
Weather refers to the daily changes whereas climate is the long terms change
-Climate relates more to global warming because the long term outcomes are changing to climate change
Explain how the Earth's atmosphere varies as a function of height.
The Earth's atmosphere has different layers as it gets higher and higher. For example, the troposphere, the closest layer, is responsible for weather
Describe the major differences between the geologic activity of Venus and Earth.
Venus has blob tectonics as opposed to Earth that has plate tectonics --- this is clue to lack of water on Venus. Another difference is the fact that impactors have a lot harder time making it through Earth's atmosphere
In addition to thermal escape, what are two other atmospheric sinks?
1. Condensation
2. Weathering
Explain why astronomers like to build telescopes with the largest diameters and highest elevation possible.
So they can see wider and closer to other objects (one rewarded 1/3 points)
The temperature of a gas is proportional to the kinetic energy of the gas particles. The kinetic energy is proportional to the mass of the gas particles times the velocity squared. Using these facts, explain why gas particles which have smaller mass escape more easily from planetary atmospheres.
Gas particles that have smaller mass escape more easily because they are too hot and moving too fast for the atmosphere to hold. (reward 2/3)
Pick two planets from Venus, Earth and Mars, and describe the major differences between their atmospheres.
Venus:
-Atmosphere mostly made up of C02
-Doesn't interact with surface
-No ozone
-Very thin
-Opaque

Earth:
-Very thick
-Interacts with surface giving us weather
-Ozone to protect from infrared
-Very thick
-Many layers
Describe the fives stages and approximate timeline of planetary evolution.
-Origin - 4.5 Byrs
-Dissociation - 4.5-4 Byrs
-late heavy bombardment: 3.8-3.9 Byrs
-The big chill: 3.0 - present day Byrs
Describe the evidence that the Moon lacks an iron core, and what this implies for the formation of the Moon.
-Involves is k-value of .39
-This value implies that it is a uniform sphere
-This implies that during the great impact/formation of the moon, earth took all of the iron
Explain the origin of tidal forces.
-It's due to the gravitational pull between the moon and the Earth.
-Eventually the pull will be a zero and there will be nor more tides
Describe the advantages of studying moon rocks returned by the Apollo Mission over measuring the Moon from afar with telescopes.
Because since we have the ability to go to the moon and find out the absolute ages of the rocks of the moon and we can use them to determine the ages of the other planets. (Ancient sediment prototype)
You were presented with a lot of evidence that supports the theory that a 10km object hit the Earth 65Myrs ago with devastating, widespread effects, altering the course of life on this planet. Had this impactor hit a world like the Moon or Mercury, the effect of the impact would be minimal, and very localized. Why then did this relatively small impactor have such. large effect on our ecosystem?
This impactor had such a large effect on our ecosystem because of our atmosphere. (2/3 points rewarded)
Describe two (2) pieces of evidence you were presented with for the impact mentioned in the previous question and explain why this evidence points to an asteroid impact?
Answer?
Most terrestrial world retain the scars of impacts from very large objects. Venus does not. Briefly explain why.
Because every 0.5 Byrs Venus basically turns into a big fire ball and explodes.
Explain why the initial Apollo Mission were sent to the mare, while later missions were sent to craters
Sent to mare because it was easier to land on, then as technology developed it allowed them to be able to land in craters.
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