# Astronomyfinal.txt

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1. This question deals with the tidal effects of the Moon on the Earth.
Explain the source both tidal bulges on the Earth (briefly explain each separately).

During full moon, would we expect to see higher amplitude (spring) tides or lower amplitude (neap) tides?
• Side facing the moon: Gravity of the moon is stronger so it pulls more
• Side opposite the moon: Less gravity but bulges out because of the stress put on the center pulling earth apart
• Higher spring tides: sun's gravity is working with the moon
2. The orbital period of Jupiter’s Moon, Io, is 10 hours. Suppose Jupiter were twice as massive and twice as large as it is today.
Would The orbital period of Io would be (longer, shorter, the same). Explain
• Longer:
• Angular momentum: m*v*r
3. Astronaut on the surface of the Moon, it appears that the Earth remains stationary in the sky, although during the course of a month, it appears to grow slightly larger and then slightly smaller in angular size. Explain
• Moon does not circle the earth in an exact circle
• Moon goes around in an ellipse or oval shape
4. the Moon is about twice as far away from the Earth as it was when you left. Since you weigh about the same on Earth as you did when you left, you know that the mass of the Earth hasn’t changed.

When you left, the orbital period of the Moon was about 30 days. Has it increased, decreased or stayed the same since that time? Explain your answer.

In order to impress the local population, you predict the day and time of a solar eclipse. Will the eclipse be annular or total? Explain your answer.
P^2=a^3 (a is the average distance from earth and P is orbital period)

Annular eclipise and only small region of the earth would see it because the moon if farther and has a smaller angular size
5. Cargo Cult Science
Explain why planes don't land
• Islander's think having runway and controller will bring planes
• Ask not what is there but what is not
• Explain Human and instructions
6. Cargo Colt Science
Mr. Young's Experiment and why you cant ignore his work
• Rat Running
• 3rd corridor
• food through sound
• put sand
• if you ignore it then your experiment would not be controlled
7. Cargo Cult Science
Milikan oil drop experiment and why it is so embarrassing for scientists
• Measure electron charge
• oil drops
• Viscosity of air
• delayed the discovery of the true size of an electron charge
8. Radiative Forcing? Positive vs. Negative and examples of each
• Positive: warming, icebergs melting
• Negative- cooling, low clouds
9. Evidence in our atmosphere that suggests recent warming of the past is not due to changes in the solar activity?
• Greenhouse effect
• CO2
• Methane
• Nitro
10. If we stop emitting carbon altogether today, the climate would continue to warm for at least another couple decades, why?
Ocean's heat plus CO2 will keep the heat going
11. How nuclear fission generates energy (exactly where does the energy come from)
• Neutron accelerated into an atom of fissionable materal that causes the breaking appart of the nucleus into two atoms of lesser material, and starts a chain reaction
• E=mc^2
12. What prevents most countries from having nuclear reactors or weapons?
• Getting U235 is hard
• Difficult to separate isotopes
• Expensive to make and maintain radioactive material because it decays
13. Enriched vs. Depleted Uranium and what are their main uses?
• Enriched: higher concentration of U235
• Used for nuclear fuel or super enriched used for nuclear weapons
• Depleted: Lower concentration
• Often used by the military for armor piercing projectiles
14. Why does nuclear fusion reactions require extremely high temperatures?
• Temp is a measure of the average kinetic energy of particles
• So by heating the nuclei they gain enough energy to overcome the electromagnetic force that repels them from eachother
15. Underground caverns as a way of storing solar energy
• Put highly compressed air created with power generated during the day into the caverns
• At night use this pressure and a lil natural gas to turn turbines during the times when you have no solar energy
16. How can salt be used to store solar power
• Use mirrors to magnify pipes filled with liquid producing steam that turns a turbine
• Use solar heat to heat up salt to a molten state and it will loose the heat slower and so u can use the heat from the salt when you don't have the solar power
17. Transition to solar energy infrastructure would result in lower US energy consumption by 2050
• Save in: delivery, refining, and storage costs of petroleum and coal
• supply 65% of US electricity and 35% of total energy
18. Arguments the authors use to justify the \$420 bil price tag that it would cost to totally switch to alternative energy
• Foreign oil dependence cut from 60 to 0
• Global tensions and military costs lowered
• Massive trade deficit reduced significantly
• Green house gas emissions slashed
19. Written records from 100s of years ago still useful why
• temp really important to them for survival
• record dates of cherry blossoms, freezing and thawing of lakes, and the state of the wine harvest
20. What do ice layers and tree rings tell us?
• Ice Layers: thicker layers means there was a warm spring which melted more snow and produced more mud
• Tree rings: narrow bands meant that the spring and winter were dryer, and thicker rings meant that there was a lot of precipitation that spring and winter
21. Keeling curve? and why does it go up and down during the spring and fall
• Keeling curve: measure of CO2 in the atmosphere over a period of years
• Down during spring because the trees are growing and absorb the CO2
• Up during the fall because the plants are dieing off and are absorbing less CO2
22. How do we used Ice core measurements to estimate the CO2 content in the atmosphere hundreds of thousands of years ago? and how does today compare to the past 450,000 years
• Bubbles trapped in the mud frozen in the ice cores
• prior to the industrial revolution, CO2 levels were much less
23. Positive feedback vs. Negative feedback
• Positive: earth warms, ice melts, exposes more dark ocean, absorbs more heat, earth warms more
• Negative: earth warms, creates more water vapors, low thick reflective clouts are made, earth cools
24. Why used instruments attached to telescopes to gather light instead of looking through an eyepiece with our eye
• Recorded images
• timing
• spectra
25. What causes stellar images to appear blurred?
• Blurring of images by atmospheric turbulence
• wind and other air currents bent the light in multiple directions
26. Why don't planets twinkle like stars do?
Planets are closer and have measurable angular size
Do opposite dance of the light so we can clearly see the image
28. Interferometry?
connection of multiple radio telescopes to achieve the angular resolution of a much larger telescope
29. Two laws that relate to the spectral curve
• Stefan-boltzmann law: each square meter of a hotter object's surface area emits more light at all wavelengths
• Wien's Law: Hotter objects emit photons with a higher average energy (shorter average wavelength)
30. (1) Given the condensation temperatures for the four main components of planets (metal, rock, ice and gas) and an indication of the temperature in various parts of the solar nebula disk, be able to identify and explain which components you would expect to condense into solid form at various locations in the solar system.
Hydrogen and helium gas make up about 98% of the solar nebula's mass and does not condense. Therefore most of the nebula remains gaseous. The other materials can, however, condense into solid materials whenever the temperature allows. Close to the sun, where temperatures can reach and upwards of 1600 K, it's too hot for anything to condense down to anything other than gas. Near Mercury's orbit, it is possible for somethings to condense into tiny, solid particles, but the other types of rock and hydrogen compounds remain gaseous.(500-1300K) Around Venus, Earth, and Mars more types of rock and metal condense. Around the asteroid belt area, temperatures are perfect for dark, carbon-rich minerals to condense along with minerals containing small amounts of water. The frost line (-150 K) marks the boundary where it is possible for hydrogen compounds to condense into ices. This line is between the orbits of mars and jupiter. Everything beyond that is made of mostly metal and ice, since it is more easily formed in that area of the solar system.
31. 2) Explain how evidence found in meteorites tends to confirm our ideas about the accumulation phase of the origin of the solar system.
Theoretical evidence of this comes from computer simulations of the accretion process. Observational evidence comes from meteorites that seem to be surviving fragments of the early periods of condensation. These meteorites contain metallic grains embedded in rocky minerals, just as we expect for the planetessimals of the inner solar system. Meteorites that are thought to come from the outskirts of the asteroid belt contain abundant carbon-rich materials, and some contain water. This is also what is expected from planetessimals of that region, so the compared evidence supports the theories.
32. (3) Name and briefly explain three reasons why Jupiter is so much larger than the Earth. As part of your answer, be sure to explain both ways in which ice particles make it easier for larger planets to form.
1. The condensation of ice meant that there was more solid material.2. Gravity then drew gas around the ice-rich planetessimals, making them much more massive then Earth. Then they collected Hydrogen and Helium, which then made the gravity greater than what it was even more!3. They collected so much gas that they bare little resemblance to their icy seed. they have come to be surrounded by a disk of gas
33. 4) Explain why lower mass gas particles in a gas tend to move more quickly than high mass gas particles.
Since the lower mass gas particles have less mass to heat up, the heat around them is absorbed faster and therefore, they move much faster than higher mass gas particles.
34. (5) Name and explain two reasons why the Earth cannot accumulate Hydrogen gas while Jupiter can. One has to do with temperature, the other with escape velocity.
1. One reason that earth cannot accumulate Hydrogen gas is because of the temperature of the space around it. Hydrogen cannot condense into solid form while it is around the orbit of earth, it is simply to warm for this to happen. This changes, however, around the orbit of jupiter. This is where the frost line is around, therefore hydrogen can condense into solid particles, making them more susceptible to being collected by a planet.2. The other reason that earth can't collect hydrogen is because, since the gas is hotter closer to the sun, it moves more quickly and can escape the gravitational pull that earth has on it. Jupiter's escape velocity is much higher than the earths, so it can pull it in easier. Not to mention that the hydrogen in solid form (which it would be around Jupiter) is going much slower than it is in gas form (around earth)
35. (7) Explain how we use Doppler shifting evidence to deduce the existence of planets around other stars. How do we estimate the mass of the companion? How do we estimate the distance from the companion planet to its parent star?
It measures the gravitational effect a planet has on a star by detecting doppler shifts in a stars spectrum. We estimate orbital distance using Newton's version of Kepler's third law. We estimate the mass of the companion using the doppler technique, but only at an angle. We generally know the masses of the stars with extra solar planet. Doppler data tells us the orbital period, that way we can figure the orbital distance. To estimate the actual mass of the planet, you must view it at an edge on angle. If it is not measured like this, the minimum mass of the planet is measured instead of its actual mass
36. 8) Explain why we cannot necessarily believe that indirect observations of planetary companions via Doppler wobbling are truly planetary companions. Are our assumed companion planet masses higher or lower than true planet masses in tilted systems? Explain.
We can only observe doppler shifts if the system is not viewed from a face-on angle. We can only tell the stars orbital velocity if we are at an edge on angle. The doppler shifts always tend to underestimate the planets' mass, this means that the estimated mass is always under the true mass.
37. (9) Explain the details and significance of the discovery of an eclipsing (or transiting) extrasolar planetary system. How did Astronomers know just by looking at the light curve that this was an eclipsing system (how is this dip different from other variations in a star's brightness)? Why was this discovery important for extrasolar planet hunters?
It requires many repeated observations because of intrinsic light variations in stars. If dimming occurs with a regular period, it is most likely the orbital period of a planet. It was impoortant because it told us the mass from the doppler technique is the planets true mass. The dips in brightness let us see the planets radius, volume, and composition.
38. (10) What is a half-life? Be able to work your way through an example of a radioactive parent isotope sample as it decays into stable daughter atoms. For example, "The half-life of a parent is 4000 years. The original composition is 280 parents and 50 daughters. The current composition is 35 parent atoms. How old is the rock, and how many daughter atoms are present?"
P. ATOMS YEARS280 0140 400070 800035 12000--------------------The rock is 12000 years old approx.TO FIND DAUGHTERS...Original amount - final amount = daughters from half lifes + daughters you had originally = daughters you have now.....280 - 35 = 245 + 50 = 295 Daughters
39. (12) Your book's chapter 8 gives another examples of how we can use physical clues to guess the original composition of a rock. Explain, for example, how we know that the original amount of argon-40 gas in a rock is zero when the rock first solidifies (and what assumption do we make about heating).
It takes about 1.25 billion years for half of potassium-40 to decay into argon-40. Potassium-40 is a natural ingredient in many rocks and minerals, but argon-40 is a gas that never combines with other elements, so if it is in minerals on the earth, you can bet it came from decaying from potassium-40 rather than being there all along. An assumption about argon-40 is that it has not escaped due to heating.
40. 13) Explain why Argon gas is a tracer of the Earth's original atmosphere. In other words, what two properties of Argon gas (name and explain) have allowed its abundance to remain constant over time while all of the other components of the atmosphere have changed radically?
It never combines with other elements and it does not condense in the solar nebula. It only forms from other elements decaying. We can then trace what the original elements were from how much is decayed...etc.
41. 14) According to the International Astronomical Union (IAU), what is the official definition of a planet now and why does this definition exclude Pluto from having the status of a planet?
The members of the IAU defined a planet as a body that orbits a star, is large enough to be round, and has cleared other bodies out of its neighborhood. This excludes Pluto from being a planet because it is surrounded by other "bodies" and is unable to clear a big enough path for itself.
42. 15) It was once thought our solar system had over 20 planets before the definition of planet was last modified in 1852. Explain what all of these extra planets were and why they were demoted from planet status.
These extra planets were all thought to be Kuiper Belt Objects. They were all demoted from planet status because they were all surrounded by objects of the same kind...it made it very hard to distinguish between planets and asteroids.
43. 16) What triggered the change in definition of planets that now excludes Pluto?
When astronomers began looking past pluto and found the kuiper belt. This belt housed many icy planets that were great in number and whos' orbits didn't match anything else in our solar system. This is what ignited the debate between what is a planet and what isn't. Poor pluto had to go. :(
44. (17) The authors propose an improvement of the definition of planets based on a factor represented by the greek letter mu. What is "mu"?
The ratio between the mass of a body and the mass of all other bodies that share its orbital zone can be abbreviated μ
45. (18) Some astronomers argue that planets should be defined only by their intrinsic properties (such as size, shape or composition) rather than by their location or surroundings. What is the authors' counterargument to this idea?
The author argues that if they say location/surroundings aren't important, then how would they classify what a moon is and isn't? Also, the planets location in relative position from the sun determines what it is made of and what can be found on the surface. This clearly makes location and surroundings an important part in classifying planets or not.
46. 19) Explain how the maria on the Moon formed and why their appearance differs from that of the lunar highlands.
The lunar maria formed from large impacts creating impact basins that were flooded by lava. Not many craters appear on the surface of the maria due to the lava flow. The lunar highlands, however, are heavily cratered and ancient. This makes the two look very different from each other.
47. 20) Explain why the surface of the moon maintains a record of the era of early bombardment (the first half-billion years after the formation of the planets) while Earth's surface does not.
This is due to weathering. The reason earth shows hardly any of these early formation craters and such is because the water on its surface has been flowing since it happened and has weathered it all away. Since there is no water/wind on the surface of the moon, there is not weathering that occurs, so everything is still clearly visible.
48. (21) Explain how the crater density of both the maria and highlands, combined with solidification ages of moon rocks from these regions, leads astronomers to believe that the cratering rate on the moon has not been constant over time and that there was an era of early heavy bombardment.
during heavy bombardment, craters covered the moon's surface. The moon's interior had already cooled, so there was not any molten rock to flood the craters. Lava floods came later due to the heat released by radio active material under the surface. The lava then welled up through the cracks of the maria, filling in the craters and forming the semi smooth surface.
49. 22) What discovery did the Magellan spacecraft make about the recent geological history of Venus?
Magellan discovered that Venus's surface had been essentially "repaved". It has the same surface everywhere on the planet which was said to be created 750 million years ago.
50. (23) What recent evidence discovered in Antarctica implies that life may have once existed on Mars?
A meteorite from mars showed evidence of primitive bacteria life on mars.
51. (24) Explain how the Earth's magnetic field interacts with the solar wind to both protect life on Earth and create the aurorae visible in the atmosphere in the North and South polar regions.
It creates a megnetosphere that diverts the path of high energy charged particles coming from the sun. It also protects the Earth's atmosphere from being stripped away into space. The aurorae are the charged particles being deflected away from earth.
52. (25) What is the ozone layer, and why is it important for life on Earth? Explain how the production of Chloroflourocarbons (CFC's) results in the partial destruction of Earth's ozone layer.
The ozone layer is a protective shield from the sun's harmful UV rays and other cosmic radiation. CFC's can cloud up the atmosphere and make it harder for the ozone to absorb UV rays, letting more into the ozone and in turn, down to the surface!
53. (2) Name and explain the reason why Jupiter and Neptune have such different colors, despite the fact that both a\re made up of almost exactly the same substances.
Neptune has 20% more methane gas than Jupiter and methane, which absorbs red light and reflects blue, makes Neptune bright blue. Also, Neptune is so cold that any cloud layers similar to those of Jupiter would be buried too deep in its atmosphere for us to see.
54. (3) Jupiter has a very rapid rotation rate and an extremely strong magnetic field. Besides fast rotation, what other property must a planet have in order for it to generate a strong magnetic field? Jupiter is composed of about 90% Hydrogen. Explain why this gas helps Jupiter generate a strong magnetic field.
Answer: Jupiter also has a molten core that combines with its rapid rotation to create a magnetic fieldIn addition to rapid rotation, a planet must also have an interior region of electrically conducting liquid to have a magnetic field. Jupiter’s internal magnetic field is generated by electrical currents flowing in the planets outer core of metallic hydrogen, which is very thick.
55. (4) Jupiter and its volcanically active moon Io are both actually emitting more energy than they absorb from sunlight. Explain the source of internal heat on Jupiter. Explain the source of internal heat on Io.
Answer: Io’s internal heat comes from tides on Jupiter. Jupiters comes from gravitational contraction.1.Jupiter’s large size means it loses internal heat very slowly but the most likely explanation for Jupiter’s internal heat is that the planet is still contracting. Contraction converts gravitational potential energy into thermal energy.2.Io’s internal heating comes from tidal heating, which arises from effects of tidal forces exerted by Jupiter. Jupiter’s mass makes this tidal force far larger than that which weath exerts on the moon. This, coupled with Io’s slightly elliptical orbit, causes Io to be continuously flexed. This constant flexing heats the interior.
56. (5) Although Europa’s surface is composed of smooth, virtually crater-free ice, we know that Europa’s interior is largely composed of rock. Explain how we know about the rocky interior even though we cannot actually see inside the planet. What direct evidence leads us to believe that there is actually liquid water a very short distance below the surface of Europa (I’m not asking you to describe the heating mechanism that makes the existence of this liquid water possible...I’m asking how we know the water must be there beneath the surface)?
Detailed measurements by the Galileo spacecraft of the strength of gravity over different parts of Europa suggest that Europa has a rocky interior. Magnetic field data from the Galileo strongly argues for liquid water beneath Europa’s icy shell because:Europa has a magnetic field which changes as Jupiter rotates, suggesting that it is created or induced in response to the rotation of Jupiter’s strong magnetic field. In order for Europa to respond with a magnetic field of its own it would need a liquid layer of electrically conducting material i.e. a salty liquid ocean.
57. (6) In the film "Life Beyond Earth", we found out about the possibility on life on other worlds and also got some perspective about intelligent life on our own. On a 5-km "highway of life", what length accurately reflects all of recorded human history?
On a 5 km highway of life, all of recorded history would lie in the last few millimeters of the last half meter of the highway.
58. (7) What recent evidence discovered in Antarctica implies that life may have once existed on Mars? Explain, how a connection to Mars was made.
In April 1984 a Martian meteorite was discovered in Antarctica after having landed there 13,000 years prior. This rock is believed to have been from a warmer, wetter period in Mars’s history. Scientists claimed that it contained evidence of past life on Mars because the rock contained complex organic molecules as well as layered carbonate materials that associated with life when found on Earth. Also found in the rock were microscopic chains of magnetite crystals similar to the chains made by many bacteria on Earth. The connection to Mars was made due to the chemical composition of the rock, which was similar to that of other Martian meteorites.
59. (8) What is the habitable zone? Explain how recent discoveries of life in extreme environments (e.g. black smokers, worms in methane ice, etc.) has affected our view of a habitable zone. What is a "gravitational" habitable zone?
The habitable zone is the region around a star in which planets could potentially have surface temperatures at which liquid water could exist. With the discovery of life in black smokers and methane ice, the definition of the habitable zone broadens by suggesting that life can arise, grow and exist in harsh conditions and environments.
60. (9) What are the three ingredients necessary for life? What is a possible source for each ingredient?
• 1. Nutrient sourceElements/molecules
• 2. EnergyFrom sunlight, chemical reactions, geothermal
• 3. Liquid water
61. (10) The Drake Equation has two possible extreme interpretations, a pessimistic and an optimistic interpretation as to the value of "N". Briefly explain arguments against each of these two extreme interpretations.
Answer: Pessimists feel that there is nearly no chance of life in the universe other than our own. Optimists feel that there are quite a few but the closest are about 1500 years away.
62. (11) Explain why the number of currently existing, intelligent and communicative civilizations in our galaxy is proportional to the average lifetime of such civilizations (I’m not asking you to restate the Drake equation...I’m asking you to explain it).
It helps determine the likelihood of there being someone whom we could contact now, which is dependent on how long civilizations survive.
63. (12) Assuming that if any aliens are trying to contact us, they are using very narrow-bandwidth signals, explain why we would want to search the spectrum using very narrow bandwidth channels (even though such a search would be much more time consuming than splitting the spectrum up into fewer broad channels).
If we search specific band with channels that would and should be commonly known and recognized by any intelligent life form attempting to reach us, we will be more likely to receive signals from these narrow band with channels because their existence should be known to an intelligent life form i.e. Hydrogen line emission.
64. (13) When we search for signals from other intelligent civilizations, one of the regions of the spectrum that we avoid is the ultraviolet (UV) portion of the spectrum. Give two reasons why it would probably be a waste of time to search this region of the spectrum.
UV rays are harmful and damaging to the skin thus making them unlikely targets for use.
65. (14) What is the Fermi Paradox, and explain fully three "answers" to this paradox and the pros/cons of each being the "right" answer.Fermi’s paradox is plausible argument suggests that a galactic civilization exists yet we have found no evidence of such civilization. Why?
1.We are alone.2.No civilization has colonized the galaxy.3.There is a galactic civilization, but I has yet to reveal itself to us.
66. (15) UFO's have been seen for many years, describe three common object/effects that are commonly seen as UFO's
Bright stars, rockets, planets, balloons, birds, meteors, atmospheric phenomena or hoaxes.
67. (16) What are three of the effects that are "relative" as one travels at close to the speed of light.
• Answer: 1. If you observe anyone or anything moving by you at a speed close to the speed of light, you will conclude that time runs more slowly for that person or moving object.
• 2. If you carefully measure the size of something moving by you at a speed close to the speed of light, you will find that its length, in the direction of motion is shorter that it would be if the object were at rest.
• 3. If you could measure the mass of something moving by you at close to the speed of light, you would find its mass to be greater than the mass it would have if it were stationary.
• 4. If you observe two events to occur simultaneously, another observer moving by you may not agree that the events were simultaneous.
• 5. No information or material object may travel faster than the speed of light.
68. (17) What are the seven needs of humans for interstellar travel? How could they be achieved?
• 1. Gravity
• 2. Safety
• 3. Atmosphere
• 4. Water
• 5. Food
• 6. Energy
• 7. Stuff
69. (18) How are the rocket equation and the kinetic equation used to understand the energy needs for interstellar travel?
Answer: rocket equation: determines how much fuel a rocket must carry to reach a given velocity. Kinetic equation: measures the energy needed to accelerate a mass to light speed.
 Author: jmsweeney ID: 56195 Card Set: Astronomyfinal.txt Updated: 2010-12-15 10:14:37 Tags: Astronomy Folders: Description: Astronomy final TCU Show Answers: