Astronomy Final

From the article "SETI Searches Today": What are two reasons to search for SETI signals near the 21-cm wavelength at which Hydrogen atoms naturally emit light?

1. Because hydrogen is the most common element in the universe, this 21-cm wavelength is a very important frequency in radio astronomy - alien engineers might choose it as a logical frequency 2. Protected for radio astronomy, so Earthly interference problems are less severe there than at other wavelengths.

Explain two sources of the gases in Mercury's tenuous atmosphere.

1. Solar wind it strips material off of the surface and is added to the atmosphere. Also some material comes from the magnetosphere when charged particles from the solar wind interact with the magnetic field. Also It may come from the direct infall of comet material. 2.The outgassing of the last original volatile substances in mercury

Explain why Io orbits so quickly around Jupiter (40 hours) compared to Earth's Moon (27.3 days). Use the equation of orbital velocity.

Because the equation for orbital velocity includes the gravitational mass and the radius of the orbit. Io and Earths moon have the same orbital radius, but Jupiter is 320x more massive than Earth, so Io's velocity is much larger than Earth's moons velocity.

One possible explanation for the lack of water on Venus is that Venus never had much water to begin with, compared to the Earth. Explain two reasons why this explanation is not plausible.

1. The Copernican Principle - This principle states that Earth is not special, whatever happened on Earth, probably happened on Venus. The same sources of water that supplied Earth should have also supplied Venus. 2. Argon Reconstruction - Earth and Venus's atmosphere have the same amount of Argon molecules. The identical skeletons of the two atmospheres lead us to believe that the original atmospheres were probably similar, meaning the original atmosphere of Venus must have contained water.

From your book's chapter 8.2, name and briefly explain the two pieces of evidence that lead us to believe a giant impact was the origin of Earth's Moon.

1. The moons overall composition is quite similar to that of the Earth's outer layers - the part of the earth that would have been blasted and eventually formed the moon. 2. The moon has a much smaller proportion of easily vaporized ingredient (such a water) than Earth. This supports the impacts hypothesis because the heat of the impact would have vaporized these ingredients.

Explain the major source of Io's internal heating.

1.) Because Io has an elliptical orbit and is tidally locked it experiences tidal heating. This means that as the moon gets stretched and compressed it moves closer and further away from Jupiter. The very short period of Io causes this compression/relaxation process to happen every 2 days. 2.) Every time Io passes by Jupiter's other 2 moons, its tidal axis wobbles a little bit and creates a form of flexing.

From chapter 8.2, explain how we believe the Sun slowed down from its initially fast rotation. What observational evidence supports this model?

A magnetic field was created from the Sun's rotation, and in turn caused the formation of a strong solar wind. The solar wind blew particles that had been dragged in by the magnetic fields into interstellar space. While the particles gained angular momentum, the Sun lost some. Afterwards, the Sun was left with a diminished angular momentum and, as a result, a slower rotation.

Explain how evidence found in meteorites tends to confirm our ideas about the accumulation phase of the origin of the solar system.

A meteorite is made of small particles of metal, rock, ice, and other things. This confirms our ideas about the accumulation phase of the origin of the solar system because we believe that all the tiny particles from the protoplanetary disk such as metal, rock, ice, and gas, collide and stick together to make our planets.

From Chapter 5, section 5.2, briefly explain the difference between a particle and a wave (light has the properties of both). Also, know the simple definitions of wavelength, frequency and photon.

A particle is individual atoms, and molecules (marble, baseball ect.). Waves consist of peaks and troughs. If a particle is under a wave, it is not moving anywhere, just up and down. Light behaves as both a wave and a particle. Like a particle, photons of light can be counted individually and hit a wall one at a time. Like waves, each photon is characterized by a wavelength and a frequency. Wavelength: the distance from one trough to the next. Frequency: the number of peaks passing by any point each second. Photon: individual "pieces" that make up light.

Explain the difference between primary and secondary eclipse in a system which contains a parent star and a transiting planet. Explain how an exoplanet atmosphere can be studied by looking at a system's spectrum just before and just after a secondary eclipse.

A primary eclipse occurs when a transiting planet passes in front of its parent star, and a secondary eclipse occurs when the transiting planet is blocked by its parent star as it passes behind it. When a systems spectrum is studied just before and just after a secondary eclipse, scientists can deduce what the planet alone would look like and examine the composition of the planet's atmosphere.

Why does the Earth have a hard time capturing Hydrogen while easily maintaining an abundance of gases like Carbon Dioxide?

Because the velocity for Hydrogen is much higher on average due to its smaller mass. Because of this it is able to escape Earth's gravitational pull.

More from the FAQ on Meteors: (a) Observers tend to see more meteors per hour when the radiant is higher up in the sky instead of just rising or very low. Explain why (2 reasons). (b) What is ZHR and why is your observed number of meteors per hour likely to be much less than this? (c) What causes a meteor storm as opposed to a meteor shower? (d) Are meteor storms dangerous to observers? Explain why or why not.

A) 1. This is because meteors seen near the horizon are much farther away than those seen directly overhead, making them dimmer and harder to notice. 2. Also, the light from a meteor near the horizon must pass through much more atmosphere to reach the observer than for a meteor overhead. B) Zenith hourly Rate (ZHR), which standardizes the shower rate to optimum observing conditions. The shower rates listed are usually corrected for fully dark skies, and the meteor radiant point has been artificially located at the zenith, directly overhead. C) Meteor storms occur when the Earth crosses the orbit of the meteor stream, at the same time that the main mass of the young meteor stream is crossing the orbit of the Earth. D) No, an observer is protected by miles of atmosphere. The meteor is composed of a somewhat 'fluffy' material that readily vaporizes in the upper atmosphere.

Read the FAQ on Meteors from the American Meteor Society and answer the following: (a) Meteors tend to enter our atmosphere much more quickly in the early morning hours compared to evening hours. Explain why. (b) Why are you more likely to observe meteors after midnight compared to before midnight? (c) What is the radiant of a meteor shower, and how are meteor showers named?

A) Due to the motion of the Earth as it revolves around the Sun, the leading edge (morning side) of the Earth encounters more meteoroids than the trailing edge (evening side). B) Because many meteor shower radiants do not rise before midnight C) The point in the sky, from which (to a planetary observer) meteors appear to originate. Meteor showers are usually named for the constellation in which their radiant lies at the time of shower maximum.

Visit The Ozone Hole Tour to learn about the Antarctic ozone hole and answer the following: (a) How is ozone formed in the stratosphere? (b) What is the Montreal Protocol? (c) Summarize how ozone is lost (see the end of Part III) and what ingredients are present over Antarctica that allow rapid ozone loss. You do not need to detail any particular chemical reactions, just summarize what happens.

A. It is created when ultraviolet radiation (sunlight) strikes the stratosphere, dissociating (or "splitting") oxygen molecules (O2) to atomic oxygen (O). The atomic oxygen quickly combines with further oxygen molecules to form ozone. B. The Montreal Protocol is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances believed to be responsible for ozone depletion. C. Strong circumpolar wind called polar vortex form in middle to lower stratosphere. This isolates air over polar regions allowing polar stratospheric clouds to form. PSC's are composed of nitric acid and are crucial for ozone loss to occur. Chemical processes also contribute to ozone depletion observed in the 'ozone hole' over Antarctica and the North Pole.

From chapter 5.4, under what conditions is an absorption line spectrum seen (diagram would help)? What determines which wavelengths absorption lines appear in a spectrum?

An absorption line spectrum is seen when light from a hot source passes though a cooler could of gas. The atoms in the cloud absorb light at specific wavelengths. The clouds composition and temperature determine which wavelengths absorption lines appear in a spectrum.

One of the Astronomers featured in the article, Dave Charbonneau, is looking for planets around dim "M dwarf" stars instead of sun-like stars. Briefly describe four reasons why it may be easier to find Earth-like planets in the star's habitable zone this way.

An earth-size planet would block a greater percentage of an M dwarf star than a sun-like star. An earth-size planet would exert a greater gravitational pull on a smaller star, therefore making it easier to detect and gauge its properties. Small, cooler stars would have habitable zones that are much closer to the star, making transits more likely to be stopped. There are many more M dwarf stars in our galaxy than there are sun-like stars.

From the last part of the article, how does an electrolyzer convert electricity into stored energy? How does a fuel cell release this stored energy for use? What currently limits this kind of process from widespread use in homes?

An electrolyzer converts electricity into stored energy by running an electric current through water, splitting it into hydrogen and oxygen. The hydrogen can later be consumed in a fuel cell to generate electricity. It is challenging to both split water and "burn" hydrogen efficiently, without producing too much heat waste, which is what is limiting this process from widespread use in homes.

From section 10.6, describe the carbon cycle, which is the collection of sources that add carbon dioxide to the atmosphere and the collection of sinks that take away carbon dioxide from the atmosphere.

Atmospheric carbon dioxide dissolves in rainwater, creating a mild acid. The mild acidic rain erodes rocks, and rivers carry the broken-down minerals to the oceans. In the oceans, calcium from the broken down minerals combines with dissolved carbon dioxide and falls to the ocean floor, making carbonate rocks such as limestone. Over millions of years, the conveyer belt of plate tectonics carries the carbonate rocks to subduction zones, where they are carried downward. As they are pushed deeper and deeper, some of the rocks melt and release their carbon dioxide back into our atmosphere through volcanoes.

Explain what the authors eventually discovered by the PETM that was different from previous conclusions. Also, how does the CO2 increase during the PETM compare to today's CO2 increase, and what do the authors therefore conclude about comparisons between the PETM and the modern era changes in ecology?

Authors discovered PETM wasn't as fast and was more moderate than they thought. CO2 increase during PETM was 30%. Think about how fast the changes and heating will occur because if it happens too fast animals and plants will go extinct and create barriers in migration and adaptions

Explain why lower mass gas particles in a gas tend to move more quickly than high mass gas particles. Use the relationship between temperature and kinetic energy to help answer this question.

Because all gases have the same kinetic energy in the atmosphere. The equation for kinetic energy is 1/2mv2. Because of this, gases with a higher mass move slower than ones with a lower mass so that their kinetic energies can be equal.

Why do we think Ganymede and Callisto are larger moons (with a larger fraction of ice) than Io and Europa? How do we think they formed?

Because they are farther away from Jupiter than Io and Europa. We think they were formed like our solar system was formed, because the moons are constructed and formed in a way that is very similar to our own solar system.

Why did some observers long ago think that Venus has a moon? What was the hypothetical "Neith" as it relates to Venus? What is the currently accepted explanation of "observations" of Venus' moon? (The Nine Planets website is a good place to go for this, look under the heading "Hypothetical Planets")

Beginning in 1672, numerous astronomers had sightings of a small companion close to Venus. It was said to be ¼ the diameter of Venus and it showed the same phase as Venus. They believed it to be a moon of Venus. Later, in 1884, Hozeau concluded that it was not a moon of Venus but a planet of its own. He named the supposed planet "Neith". After detailed investigation, the currently accepted explanation is that the observations of the satellite were really just stars seen in the vicinity of Venus.

Critics of evolution wonder how a process based on random chance could result in extremely complex organisms. How do biologists respond to this argument?

Biologists respond to this argument by saying that 4 different characteristics are enough to make a wide variety of different types of organisms. The organisms with the best characteristics are able to survive, which is why there are such complex organisms. The fittest organisms (the most complex ones) are the ones that survive.

Explain why the Carbon cycle on Mars may have been broken thanks to the loss of internal heating.

Both of them are tied to the loss of internal heating so you lose the magnetic field so you aren't protected from solar wind. The carbon cycle still has the same sources like volcanism but they died away and for the source to work you need internal heat.

What are breeder reactors? How might breeder reactors overcome one of these drawbacks, and what is a major problem associated with breeder reactors?

Breeder reactors convert old fuel (depleted uranium) into new fuel (plutonium). Waste that they don't know what to do with can be converted with breeder reactors into new fuel. A major problem with this is proliferation. The plutonium that would be produced by breeder reactors can be made into dangerous weapons.

Explain the evidence from recently-observed comets (such as Halley) that implies most of Earth's water probably did not come from comets.

Comets like Halley have high percentages of deuterium. Compared with normal hydrogen, deuterium is twice as abundant in these comets as it is in seawater. It is difficult to see how the oceans could contain proportionality less deuterium, so most of the water on Earth must have come from somewhere else.

What are Deuterium and Tritium? Explain how nuclear fusion (D-T fusion) generates dangerous waste products.

Deuterium and Tritium are isotopes of hydrogen with extra neutrons. Deuterium has one extra neutron, and Tritium has two extra neutrons. When they combine together they make helium, energy, and one extra neutron. This extra neutron can be dangerous nuclear waste.

What is Deuterium? What is heavy water? One explanation for the lack of water on Venus is that the water was absorbed into the crust somehow and now resides below the surface in aquifers or underground lakes. Explain how the heavy/light water ratio tends to argue against this hypothesis.

Deuterium is an isotope of hydrogen that contains a proton and a neutron, making it heavier. Heavy water is that which contains more deuterium molecules than regular hydrogen molecules (which contain only one proton). The heavy/light water ratio on Venus argues against the hypothesis that the water on Venus was absorbed into the crust because Venus's ratio is larger than Earth's. If the water were lost into the ground, then the deuterium molecules in the atmosphere would have been lost, not the hydrogen molecules.

From Chapter 5, section 5.1 of your textbook, briefly describe the four different ways that light can interact with matter.

Emission: a light bulb can emit visible light; the energy of the light comes from electrical potential energy supplied to the light bulb. Absorption: When you place your hand near an incandescent light bulb, your hand absorbs some of the light, and this absorbed energy warms your hand. Transmission: Some forms of matter, such as glass or air, transmit light, which means allowing it to pass through. Reflection/Scattering: Light can bounce off matter, leading to what we call reflection when the bouncing is all in the same general direction or scattering when the bouncing is more random.

What arguments can you make that evolution is very unlikely to result in intelligence? What is an emergent property? Explain this concept in general, and then give one example.

Evolution may be unlikely to result in intelligence because on Earth there are billions of species that have developed but only one species has intelligence. The emergent property is that intelligence does not always come from just one individual but comes from the whole - (collective intelligence) One example is a bird. One bird doesn't look like anything, but when there are many, you can see the shape they are making. Another example is a symphony.

Explain how water can be used to store energy generated by windmills for later use when the wind isn't blowing.

Excess electricity is used to pump water from a low reservoir to one higher uphill. When the water falls back down to the lower reservoir, the water passes through a turbine that turns a generator to create electricity.

What is the Fermi paradox (Fermi's question), and what is one possible response?

Fermi questions the Copernican principle that states that there is life and civilizations elsewhere throughout the galaxy. He wonders why scientists haven't heard any broadcasts if there are so many existing civilizations. Where is everybody? We have been listening for 50 years and no broadcasts have been found yet. One possible response is that others are not broadcasting because they have chosen not to for some reason or do not want to reveal their existence.

What evidence on the surface of Mars indicates Mars once had a thicker, warmer Earth-like atmosphere? Explain.

Fossilized river channels found on Mars tell us that liquid water once existed on its surface for a long time. This tells us that its atmosphere was once like that of the Earth, meaning it was thicker and warmer.

Explain Stephen Hawking's argument regarding why we should not necessarily be attempting to contact extraterrestrials but instead simply listening.

Hawking pictures the aliens as having a huge spaceship as that they would most likely be in need of resources. Therefore, that any aliens who visit us would not visit peacefully and that it would not end well for us.

What is an example of an observation Galileo made to show that objects in the Universe are not static like paintings on the inside of cathedrals?

He found sunspots in the sun. Also he discovered that the Sun spins like other planets. He made the observation that Earth is one of many worlds.

Briefly explain three possible ways early Earth's water could've been "lost" and not become a permanent part of Earth's oceans.

Ice clumps collided with Earth during the initial formation of the planet, putting large quantities of water into the atmosphere in the form of steam. Then much of the water was lost back into the atmosphere and the molecules destroyed by ultraviolet radiation. Some molecules survive though and condense into oceans. Meteorites that contain .1% water by weight bombarded the Earth, so technically the Earth would be composed of about 4 times the amount of water that is held today. Perhaps half an ocean of moisture became trapped within minerals of the mantle. Water may also have taken up residence in Earth's dense iron core, which contains some relatively light elements like hydrogen.

Even if we were to stop emitting Carbon altogether today, the climate would continue to warm for at least another couple of decades, if not longer. Explain why.

If humans were to stop emitting Carbon altogether today, the climate would continue to warm for at least another couple of decades because of the natural emissions of CO2, such as volcanoes. Also changes in the oceans circulation patterns have an effect on the natural processes within climate change. Changes in the suns intensity can also have an effect on the climate.

If the Kyoto protocol were enacted, how would that change projected atmospheric concentrations of carbon dioxide over the next 100 years, compared to "business as usual" projections?

If the Kyoto protocol were enacted it would only decrease the projected atmospheric concentrations of CO2 to about 670-680 ppm. The "business as usual" projection is about 700 ppm, so it would only be decreased by about 30 ppm

Explain how we use crater density to estimate the solidification ages of planetary surfaces. Is the solidification age of each part of the Moon proportional to the crater density? Explain what the answer to this question reveals about the solar system's history.

If the cratering rate is constant, then the number of craters on a surface is proportional to solidification age. The highlands have 100x more craters than the Maria but have a solidification age of 4 billion years compared to 3.7 billion years for the Maria. This shows that part of the moon suffered from early bombardment.

From your book's chapter 8.2, explain the evidence that tells us the Moon and Earth likely did not form together simultaneously.

If the two had formed simultaneously, they both should have been created from planetesimals of the same type. Therefore, they would have approximately the same compositions and density, which is not the case. The moon's density is considerably lower than Earth's, indicating that it has a very different composition and could not have formed in the same way or at the same time as our planet.

From the reading "Philosophy and the Scientific Method," use the barrel of apples analogy to help explain the difference between "probably true" and "almost definitely true, beyond any reasonable doubt."

If there is a barrel of apples and you take one off the top and it is rotten, assuming that all of the other apples are rotten would be a statement that is "probably true". However, if you are given more information such as if the amount of time the apples have been in the basket, and what room temperature they have been in they can use this information to make a hypothesis and do research to conclude the idea that all of the apples are rotten. They could also get a sample of the apples by taking one from the top, one from the middle and one from the bottom. Having information and using scientific research like this can change your idea from being "probably true" to "almost definitely true, beyond any reasonable doubt".

Describe the evidence observed by the Mars Global Surveyor in 2000 and 2006 that led scientists to believe running water may exist on Mars currently.

In 2000, the MGS found surface features that looked like gullies on Earth that are carved by flowing water. In 2006, new data showed a light-colored material had spilled out of the gullies just a few years ago.

Name and briefly explain the two things necessary in a planet's interior that enable a planet to have a magnetic field.

In order to have a magnetic field a planet must be spinning (or rotating) so that it has motion and it must have internal heat so that it has charged particles.

From Chapter 4, section 4.3, explain how the Kelvin temperature scale is related to Fahrenheit and Celsius. What is absolute zero? One advantage of the Kelvin scale is that it never uses negative temperatures. Explain why this makes sense using the definition of temperature from question 1.

In science the Kelvin temperature scale is used. It does not have any negative temperatures because it starts from the coldest possible temperature, which is called absolute zero. So in Fahrenheit the absolute zero is -459.67 degrees. This makes sense using the definition of temp because the average kinetic energy of the particles cannot be negative.

From Chapter 5, section 5.2, explain how infrared light compares to visible light in the electromagnetic spectrum. Specifically, is it longer or shorter wavelength? Higher or lower frequency? Higher or lower energy?

Infrared light has a longer wavelength than visible light. Infrared light has a lower frequency than visible light. Infrared light has lower energy than visible light.

Explain the origin of Io's plasma torus.

Io is very hot so when a volcano erupts, it spews heated particles along with plasma into space since Io has no atmosphere. Then the torus forms because the heated particles cannot cross the magnetic field of Jupiter.

From Chapter 12.4, explain why the presence of unusually high amounts of iridium in the boundary layer from 65 million years ago led scientists to believe a large impact occurred at that time on Earth. Also list three other pieces of evidence in support of this hypothesis of a large impact.

Iridium is a metal that is common in meteorites but rare on Earth's surface. Since it is rare on Earth, this abundance of iridium must have come from a large meteorite impact. The age of the sediments rich in iridium coincide with the time that the dinosaurs went extinct. 1.) The same boundary layer contains high amounts of gold and platinum. (Metals commonly found in meteorites) 2.) The layer contains grains of "shocked" quartz: structure indicates they experienced the high-pressure conditions of an impact. 3.) The layer contains a type of spherical rock droplets that are known to form when drops of molten rock cool and solidify in the air.

Explain two lines of argument that support the idea that the increase in Carbon Dioxide in Earth's atmosphere over the past 200 years is largely due to human activity as opposed to a natural process or cycle.

Isotopic Fingerprint: Fossil fuels and natural sources of CO2 have a very different fingerprint. Fossil fuels are composed of 100% C-12 and 0% C-14, while natural sources are composed of 99% C-12 and 1% C-14. Looking back at isotopic fingerprint over the years, we can see that the amount of C-14 has been dropping. Based off this information we can see that the CO2 increase is because of us, because there have been more fossil fuels in the air lately, which is why the C-14 levels are lower. A graph showing the CO2 abundance over the years is smooth, not spiky. Meaning that it is consistently growing, and not going up and down over time.

Explain the evidence that indicates Mercury has a source of internal heat, unlike Earth's moon.

It has a magnetic field caused by the expanding and contracting of its iron core.

For each of the five ways that gas can leave a planet's atmosphere, explain why Argon does not leave from the atmospheres of Earth and Venus while other gases (like water, oxygen, carbon dioxide or nitrogen) can leave in some cases.

It has no cycle and is not affected by sources or sinks. Not affected by thermal escape - too heavy/slow to beat escape velocity. Not affected by Solar wind stripping - b/c of Earth's magnetic field. Low freezing temperature - doesn't condense. It is a noble gas - does not chemically react with anything. Not affected by large impacts - b/c so heavy and slow.

Why is it difficult to contain fusion reactions? Explain inertial and magnetic confinement.

It is difficult to contain fusion reactions because the gas is so hot. They use inertial and magnetic confinement to contain them. Inertial confinement is when you put the atoms in a pellet and fire lasers at the pellet. Magnetic confinement is when you take all the electrons out of the atoms, so they are only positively charged. You then put them inside a device with a magnetic field line because charged particles cannot cross magnetic field lines.

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 the planet. This discovery was important because it told us the mass from the Doppler technique is the planets true mass. The dips in brightness let us see the planet radius, volume, and composition.

Read http://www.physics.upenn.edu/nineplanets/venus.html and briefly explain why no small craters exist on Venus.

It seems that small meteoroids burn up in Venus' dense atmosphere before they are able to reach the surface. If they do reach the surface, they usually break up in the atmosphere.

Explain what "dynamical heating" is and how Jupiter is likely responsible for the formation of the asteroid belt and also the relatively small size of Mars.

Jupiter disturbs the asteroid orbits by heating up the asteroids and causing them to move quickly in random directions. This creates high-speed collisions, which are not constructive. This explains the formation of the asteroid belt and why there is no planet in its place. Because Mars is close to the asteroid belt, all of the non- constructive collisions made it harder for Mars to grow and accumulate material.

Seen here and explained more fully here are the aurorae on Jupiter. What is the origin of the auroral ovals, streaks and dots on Jupiter?

Jupiter's aurora is produced when high-energy electrons race along the planet's magnetic field and into the upper atmosphere where they excite atmospheric gases, causing them to glow. Jupiter's aurorae include several bright streaks and dots - produced by electric currents generated by the moons.

Visit http://www.nineplanets.org/jupiter.html and describe what is thought to be the main source of Jupiter's internal heat.

Jupiter's internal heat is generated by the Kelvin-Helmholtz mechanism, the slow gravitational compression of the planet or star caused by the cooling of its surface. The cooling causes the pressure to drop and the star or planet shrinks as a result. This compression, in turn, heats up the core of the planet. The kelvin-helmholtz mechanism, the slow gravitational compression of the planet or start by the cooling of its surface. The cooling causes the pressure to drop and the planet/star shrinks as a result. This compression, in turn, heats up the core of the planet.

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.

Larger Feeding Zone - Jupiter has a much larger area to draw from while it was forming. Ice Advantage - where Jupiter is located from the sun, it is cold enough for ice to condense. - Ice is sticky so it accumulates easier. - Ice is more abundant that metal and rock Jupiter is massive and cold enough to capture and hold hydrogen and helium gas.

From the article "A Big New Step in the Search for ET": Describe two arguments in favor of Optical SETI searches and why other civilizations might try to use optical wavelengths instead of radio to communicate with us.

Laser signals could be as efficient and economical as radio for sending messages between the stars. Other civilizations might use optical wavelengths for two reasons: 1.) Laser pulses would be plainly artificial because nothing in nature is able to produce anything like them. 2.) The brightness of the laser pulses would cause them to stand out against other background light.

From section 5.4, what are the two laws of thermal radiation? Explain how we can use a thermal radiation spectrum for an object to determine the temperature of the object.

Law 1: each square meter of a hotter objects surface emits more light at all wavelengths. Law 2: Hotter objects emit photons with a higher average energy, which means a shorter average wavelength. We can use a thermal radiation spectrum for an object to determine the temperature of the object because thermal radiation spectra depend only on temperature. We can estimate the temperature simply from the objects color too. Hotter objects emit more light at all wavelengths and the biggest difference appears at the shortest wavelength.

According to the diagram on page 63 of the article (page 6 of the pdf), why does the Southern hemisphere of Mars experience warmer summers compared to the Northern hemisphere? From the textbook's section 2.2 (pages 36-37 specifically), explain why Earth does not behave similarly to Mars.

Mars' perihelion is during the Southern summer of Mars. The orbital orientation also shifts every 10,000 years or so and is currently shifted towards the Southern hemisphere. Earth's seasons are caused by the axial tilt and not distance from the Sun. There are no variations caused by distance from the Sun because the southern hemisphere has more ocean and keeps its climate moderate.

Explain why we think substantial quantities of sulfur may be present in the interior of Mercury (this has to do with its magnetic field).

Mercury has the most powerful magnetic field of all the terrestrial planets except for Earth. Earth's magnetic field is generated by electrically conductive molten metals circulating in the core (self-sustaining dynamo). If Mercury's magnetic field has a similar source, than the planet must have a liquid interior. A solid core cannot support a self-sustaining dynamo. This contradiction suggests that other materials like sulfur that cause iron to remain liquid at low temperatures are present in the core.

Explain how Mercury's unusual orbit contributes to its tidal heating.

Mercury's orbit around the sun is slightly elliptical and is 88 days long. Mercury rotates every 59 days. This causes its tidal bulges to point at the sun when it is closest to the sun (perihelion), and its tidal bulges to point away from the sun when it is furthest from the sun (aphelion). The changing from perihelion to aphelion creates a stretching and compressing of the metal in Mercury's core, known as tidal flexing, which in turn generates heat.

From section 10.2, briefly explain three things that can change the Earth's reflectivity, aside from melting ice or freezing water.

Microscopic dust particles (called aerosols) released by volcanic eruptions can reflect sunlight and cool the planet. Smog particles can act like volcanic dust, reflecting sunlight before it reaches the ground. Deforestation also increases reflectivity, because it removes sunlight-absorbing plants.

From the reading "Cargo Cult Science", briefly explain the story of the Millikan oil drop experiment and the subsequent history. Explain why this was such an embarrassing episode for scientists.

Millikan was measuring the charge of an electron by an experiment of falling oil drops, and when he got his answer it was published. When other scientists emulated the experiment, they got much larger numbers in their results. These scientists found reasons to go back and get different results in order to get a number closer to Millikans. This was embarrassing because scientists were deducing information based off a publication rather than the results at hand.

From the reading "Cargo Cult Science", briefly summarize the story of Mr. Young's experiment and why those who ignore his work cannot really trust their conclusions.

Mr. Young wanted to train rats to go to the third door in a maze, and through trial and error he managed to do so. He made the doors the same, covered up the smell of the cheese, and even put the entire container on sand in order to make the experiment's conditions completely controlled. The scientists who went back to "normal" rat running experiments can't trust their results because their experiments aren't controlled.

The authors propose an improvement of the definition of planets based on a factor represented by the greek letter mu. What is "mu"?

Mu is the ratio between the mass of a body and the mass of all other bodies that share its orbital zone. It can be abbreviated as µ.

In the solar nebula model, explain why the planet Neptune is smaller than Jupiter instead of the planets getting larger and larger as one looks further away from the Sun.

Neptune density much smaller and accumulation is very slow. when sun ignited solar winds blew hydrogen and helium out of system before neptune had chance to grow.

Will this "greening hypothesis" enable the problem to essentially solve itself by taking all the excess Carbon out of the atmosphere? Explain.

No, because we already have excess CO2 and the plants haven't been able to get rid of it yet. Adding more CO2 into the atmosphere will speed up the growth of plants/trees, but then there is even more excess CO2 in the atmosphere.

Explain how nuclear fission generates energy (where, exactly, does the energy come from in the reaction). Also, explain briefly how nuclear power plants convert this energy into electricity.

Nuclear fission is when uranium is split into smaller parts, neutrons, and energy because the mass has decreased by a very small amount. The reaction from the nuclear fission of the uranium is put into fuel rods. These fuel rods are put into a tub of water. The radioactivity of the fuel rods boils the water, creating steam that moves a turbine, which creates the energy.

What prevents most countries from having nuclear reactors or weapons?

Nuclear proliferation and nuclear meltdowns prevent countries from having nuclear reactors and weapons. Nuclear meltdowns is when the water starts leaking our of the bins that have the fuel rods in them.

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.

On Jupiter, the temperature is colder so the gas's velocity is slower making it easier to accumulate. On Earth, the temperature is warmer so the gas's velocity is faster making it harder to accumulate. The escape velocity of Jupiter is much higher than Earth's escape velocity so it is harder to escape from its gravitational pull.

Name and briefly explain two pieces of evidence that Titan has ongoing volcanism on its surface.

One sign of plate tectonics is at least two areas look like frozen volcanic flows, they are brighter in near infrared light than any other area. Another sign of geological activity is the almost complete lack of impact craters, showing that volcanism paved over them.

One potential consequence of global warming will be a relatively fast rise in sea levels as a result of melting ice (mainly in West Antarctica, since it is currently on land) and one other mechanism, described in the first few paragraphs of the following scientific discussion summary: http://www.faqs.org/faqs/sea-level-faq/. Read these paragraphs and summarize in a sentence or two another mechanism besides melting ice that may cause sea levels to rise as the Earth warms up.

Other occurrences that could cause the sea levels to rise as the earth warms up is the temperature of the water changing. Colder water is denser, so the same mass of water takes up less space. So if the water were to warm up it would take up more space and cause the sea levels to rise.

From http://www.pbs.org/wgbh/nova/education/activities/3113_origins_06.html, answer the following: Which gas, oxygen or ozone, is probably a better indicator of the existence of life on a planet and why?

Ozone. The presence of Oxygen alone can't be taken as an unambiguous indicator of life. Oxygen does not produce spectral lines that can be easily observed in the infrared part of the spectrum. However, Ozone does produce spectral features in the infrared. The ozone layer, which is located in the Earth's atmosphere, is important to life because it protects Earth from the Sun's harmful UV rays.

From the reading "Cargo Cult Science", explain "why the planes don't land" to a typical islander who might ask, in a few sentences.

Planes don't land because you have to know how things work, not just replicate the looks of them. Even though you have objects and a setup similar to an airstrip, the planes do not land because you do not understand the process and procedures necessary for flight. The reason they landed before was because there was a war going on.

From section 5.3 of your book, describe plasma and explain why matter normally takes on this form at very high temperatures.

Plasma is the type of hot gas in which atoms have become ionized. When temperatures get higher and higher, collisions can break the bonds holding electrons around the nuclei of individual atoms, allowing the electrons to go free. Charged atoms (whether positive or negative) are called ions, and the process of stripping electrons from atoms is called ionization. At temp. of several thousand degrees, the process of ionization turns an element (such as water) into a hot gas consisting of freely moving electrons and positively charged ions. This hot gas is plasma.

Read this article and describe the evidence that Mars may have once experienced plate tectonics just like the Earth. Specifically, describe what the evidence is, exactly, then explain why that evidence points to the existence of a magnetic field (describe how a magnetic field helps create such a feature in the rocks).

Plate tectonics leave a distinctive magnetic structure in the Earth's crust. A very similar signature has been found on regions of the crust of Mars. The signature come from patterns of magnetic stripping - bar-code-like stripes that are formed by sea floor spreading. They magnetize and align in the direction of the prevailing magnetic field. Patterned stripes similar to these were found on Mars, however they were much more magnetized than those on Earth - probably because Mars is richer in Iron. They were also longer and wider.

In computer models, name and explain one example of a positive feedback effect and a negative feedback effect. Why do the computer models have such a wide range of possible predictions about future temperatures?

Positive - effect positively adds to initial cause - earth warms, ice melts, darker surface absorbs more heat. Negative - effect cancels out original cause - earth warms, more water vapor, low and thick clouds, earth cools. Computer models cannot give precise answers because the varying feedbacks reflect huge uncertainties. Scientists are unsure which feedback will ultimately dominate.

Why do radio wavelengths work as the best way to communicate with potential extraterrestrials?

They are the most efficient. The only alternative form of communication would be to send a spaceship. Radio signals only take about 10 years and cost about $50. They are the best type because they are the quietest - They have very little background noise and do not scatter.

What is radiative forcing? What does "positive" radiative forcing and "negative" radiative forcing mean? Give an example of each in climate science.

Radiative forcing is the change that is caused in the global energy balance of the earth relative preindustrial times. (usually expressed by watts pre square meter). A positive radiative forcings are influences that cause the climate to grow warmer, and negative radiative forcings are influences that cause the climate to grow cooler. An example of positive forcing in climate science is an increase in greenhouse gases in the atmosphere. An example of negative forcing in climate science is when the earth is more reflective (the albedo levels are higher).

From the February 2013 Scientific American (short) article, "Ring Theory," answer the following: According to the researchers in the article, what is the likely origin of the systems of satellites surrounding Saturn, Uranus and Neptune?

Researchers determined that moon started on the edge of planetary rings. They moon then becomes bigger which leads to them getting closer to the planet, which again makes them accumulate more.

Name or briefly describe two examples of sources and two examples of sinks for Carbon Dioxide in the Earth's atmosphere.

SOURCES: - Volcanism: release carbon dioxide - Fossil Fuels: release carbon dioxide when burned - Plant Decay: plants release carbon dioxide when they die SINKS - Photosynthesis: plants absorb carbon dioxide in this process - Weathering: binds carbon dioxide to rocks; carbon dioxide is pulled out of the air by perspiration

To go back further, 1000 or more years, scientists look in places like Lake Tuborg or an old forest. Briefly describe what scientists look for when they look at ice layers in a frozen lake and tree rings in a forest. Do thicker layers/tree rings mean warmer (wetter) climate or cooler (drier) climate? Explain why for each case.

Scientists look at the thickness of space between lines in an ice core or tree rings, called layers. Larger layers or tree rings means that the climate at the time was warmer (wetter) climate.

Briefly explain why climate scientists weren't satisfied with the Kyoto treaty and also why politicians were also not satisfied (summarize one of the reasons given in each case).

Scientists were unsatisfied because the change it would make would be very minimal. Politicians were unsatisfied because some countries don't produce as much CO2 as others, and they felt like they should not need to make changes if they aren't the cause of the problem.

Explain why searches for other planetary systems so far have been biased in favor of discovering high mass planetary companions as well as planetary companions that are very close to their parent stars.

Searches for other planetary systems so far have been biased in favor of discovering high mass planetary companions because terrestrial planets cause a star wobble velocity too small to detect. Searches for other planetary systems so far have been biased in favor of planetary companions that are very close to their parent star because we have only been collecting data on most stars in this way for less than 10 years.

Explain how we use deep-sea sediment cores to indicate temperatures long ago. Also, explain why these sediment cores are the most degraded and difficult to interpret during the period when the most warming took place?

Sediments are laid down slowly and trap minerals, including the skeletal remains of surrounding atmosphere or ocean. Skeletal remains reveal temp of the water. The layers where the most extreme conditions happened during PETM were dissolved by ocean acidification and carbonate in sediments.

Describe how stable isotope siblings of parents and daughters are used to determine the original composition in a rock. For example, "When a rock solidifies, the number of parent atoms is one-half the number of stable sibling atoms. The parent has a half-life of 10,000 years. The current composition is 20 parents, 640 daughters and 640 stable siblings. How old is the rock, and what was the rock's original composition?"

Siblings are stable isotopes that are present in a rock. Their number is equal to the total number of original children when the rock was formed because they do not decay.

Explain the two chemical changes that occurred in the oceans due to the PETM warming. What were these changes, and how did rising CO2 levels cause them?

Since more CO2 in atmosphere the oceans were taking in more CO2 and warming. This extra CO2 was creating carbonic acid. Again because of the warmer temp the oxygen was depleting in the oceans and killing off plants and animals that lived in oceans and needed oxygen.

From section 9.1 of your book, explain why smaller solar system bodies (like the Moon) cool off more quickly after their initial formation compared to large planets (like Earth).

Smaller solar system bodies cool off much quicker than large ones because they have less "insulation" for interior heat to go through before reaching the surface. It is similar to the way a hot pea becomes cooler much faster than a hot potato does.

Briefly explain the catastrophe hypothesis for the origin of the solar system. Name and briefly explain two arguments that contradict this hypothesis.

The catastrophe hypothesis for the origin of the solar system is that the sun formed by itself, and then had a collision with another star. Resulting debris from the collision became a disk, which formed the planets. Two arguments that contradict this hypothesis are... - Collisions are too rare because space is too big. - And planets (like earth) wouldn't have volatiles (substances easily destroyed by heat) if this hypothesis were correct.

From section 10.2, list the three other major factors besides changes in the greenhouse effect that can cause climate change. Explain how and why a change in axial tilt of the Earth would change the climate to be warmer or cooler.

Solar Brightening: The sun has grown gradually brighter with time, increasing the amount of solar energy. Changes in Axis Tilt: The tilt in the planet's axis may change over long periods of time. Changes in Reflectivity: An increase in a planet's reflectivity means a decrease in the amount of sunlight it absorbs, and vice versa. Small tilts in the earths axis can affect climate by making the seasons more or less extreme. Greater tilt means more extreme seasons, so hotter summers, which melts more ice and causes the earth to be less reflective. A smaller tilt means less extreme seasons, which can cause ice to build up and make the earth cooler.

Name and briefly explain the two things limit the ability of the Mars Reconnaissance Orbiter (MRO) to directly identify actual flowing water on the surface?

Spectrometers may lack the spatial resolution to find narrow stripes that indicate water and the MRO orbit only observes Mars afternoons when water is probably not present at the surface.

What is the difference between spring tides and neap tides? Which type of tides should we expect to see during new moon? Full moon? 1st quarter? Explain.

Spring tides occur when the sun and the moon directly line up. Spring tides cause the tides to be larger (tidal force of the sun and the moon work together). Neap tides occur when the tidal forces of the sun and the moon work against each other and counteract, causing the tides to be smaller. New and Full Moon: spring tides. 1st quarter moon: neap tides. This is because new and full moons occur when the moon is lined up with the sun and 1st and 3rd quarter moons occur when the sun and the moon are 90 degrees away from each other.

Explain two pieces of evidence that led the author to believe the dark lines seen by the HiRISE camera, the Recurring Slope Lineae (RSL), were caused by intermittently flowing liquid water.

Streaks are found on warm, sun-facing hillsides which indicates they are caused by the seasonal melting of shallow deposits of salty frozen water. They can also form through deliquescence which is when abundant salts in the ground take in water vapor by upwelling water vapor from reservoirs.

What evidence tells us that methane "rain" may be falling at times on Titan?

Telescopic observations, and the Cassini, were able to see methane clouds in accumulation, puffing upward just like terrestrial cumulus and then dissipating as cloud droplets turned into rain. Cassini has also observed the surface darken after clouds have passed over. Aerial photographs also show that Titan's landscape has been shaped by rainfall.

How might this in turn lead to the loss of the Martian atmosphere?

The Carbon cycle consists of sources, such as volcanism and outgassing, and sinks, such as rainfall. When Mars lost all of its internal heat its Carbon sources were lost as well. However, it's Carbon sinks were not. Over time, all of the Carbon was dragged out of the air and the atmosphere eventually froze.

Explain how the Earth's magnetic field interacts with the solar wind to protect life on Earth and create the auroae visible in the atmosphere in the North and South polar regions. A diagram would really help.

The Earths magnetic field is shaped in a way that its lines enter the Earth's atmosphere near the poles. The magnetic field blocks most solar wind particles from entering its magnetosphere, however it does not block all of them, especially near the magnetic poles (North and South regions). Once charged particles enter the magnetosphere, they move along the magnetic field lines that encircle our planet (they don't like to cross them). Some of them follow the filed lines all the way down into our atmosphere near the poles. They then collide with atoms and molecules in the atmosphere and create a glow. The glowing reactions are auroraes.

What is the Faint Sun paradox and how has it been "resolved" by our atmosphere?

The Faint Sun Paradox is the disparity between the prediction that when the sun first became stable it was 30% dimmer, which would have caused the oceans to be completely frozen about 2 billion years ago, and the fossil evidence that shows that water and life were both present as early as 3.8 billion years ago. This has been "resolved" by our atmosphere because the early atmosphere contained more carbon dioxide and methane, which would have increased the greenhouse effect and kept the earth warmer.

From the same web site mentioned above, what is the origin of Jupiter's faint ring system? In other words, where do the rocky particles come from that make up this thin, dark ring?

The Galileo spacecraft found clear evidence that the rings are continuously resupplied by dust formed by micrometeor impacts on the four inner moons of Jupiter.

What is the habitable zone? Explain how recent discoveries of life in extreme environments (e.g. black smokers, worms in methane ice, etc.) has affeted our view of a habitable zone. What is a "gravitational" habitable zone?

The Habitable zone is the region around the system's star where we can expect to find liquid water on the surface. Discoveries of life in extreme environments had shown that life doesn't require sunlight. Our view of the habitable zone is bigger now. A Gravitational Habitable Zone is an area where life could survive because of the heat generated by gravitational or tidal waves.

Explain two related pieces of evidence collected by the HiRISE camera that indicates the gullies first seen by the Mars Global Surveyor are more likely related to Carbon Dioxide that liquid water flow.

The HiRISE camera showed that the gullies became active when the CO2 frost covered the ground, forming new alcoves, channels and fans. The HiRISE camera also showed that the pattern in which the gullies formed matches the seasonal distribution of CO2 frost.

What is the Keeling curve? Why does it go up and down during the Spring and Fall?

The Keeling Curve measures the concentration of CO2. It goes down in the spring because of all the plants taking in CO2, and in the fall it goes up because of the plants not being there to take in CO2.

What are the Kirkwood gaps? Explain how they are formed. As part of your answer, address the following: Why would an asteroid in one of the gaps be affected so radically by Jupiter while an asteroid just to one side or the other of a gap isn't affected?

The Kirkwood gaps are resonance gaps. Resonance refers to a force applied in a period system with the same frequency. When this force is applied, energy is transferred to the system (ex: pushing someone on a swing). The asteroids that lie in one of the gaps are affected so radically by Jupiter because their resonance frequency causes them to align with Jupiter periodically. When they align, the asteroid receives a gravitational nudge from Jupiter and it is eventually pushed out of its original orbit. An asteroid just to one side of a gap does not have a resonance frequency, so Jupiter's forces have no effect on it.

What was the political fate of the Kyoto treaty in the United States?

The Kyoto treaty was never ratified in the United States.

What discovery did the Magellan spacecraft make about the recent geological history of Venus?

The Magellan spacecraft made the discovery that sometime in the last 300 years or so Venus went through an event that melted the planet, which is why it is now very hot and dry.

Explain the reasoning that leads us to believe that a large fraction of Mercury's mass consists of iron.

The Mariner mission confirmed that Mercury has a very high density for its small size. This observation provides a fundamental clue about Mercury's interior. Because Mercury is so dense, astronomers believe that it may have the largest metallic core, relative to its size. This means that a large fraction of its core consists of iron.

What is the Mercurian Grid, and how do we think it formed?

The Mercurian Grid is a network of crosscut linear features of unknown origin. We think they formed due to a change in Mercury's surface. Mercury's crust solidified when the planet was rotating much faster. After the planet slowed to its present period, gravity pulled it into a more spherical shape. The lineaments that make up the Grid may have arisen as the surface accommodated this change.

From Chapter 12.2, briefly explain the origin of the Oort Cloud and explain why it has a spherical shape. Also explain the origin of the Kuiper Belt and why its shape is more like a disk.

The Oort cloud is a vast, spherical region of comets made up of the left over planetesimals from when the Jovian planets formed. They were flung off at high speeds in random directions creating the Oort cloud's spherical shape. The Kuiper belt is a ring of comets that orbit the Sun beyond the orbit of Neptune. It was also created by the formation of the jovian planets. They tended to keep on the orbits on which they formed - the same plane and direction as planets = disk-like shape.

What is a Q-value, and how does it relate to the viability of nuclear fusion as an energy source?

The Q-value is energy output divided by energy input. You want this number to be greater than 1.

What makes the surface of Europa so young (such a low crater density, bright coloring)? Explain why we think Europa is one of the most likely objects in the solar system besides Earth to have life as we know it.

The amount of tidal energy that Europa has allows liquid water to form under the surface. This water can well up between cracks in the surface like lava. We think Europa is one of the most likely objects to have life because it has the three things necessary for life: energy, water, and organic molecules.

From chapter 13.1 of your textbook, describe the astrometric technique for detecting extrasolar planets (what do we measure and how). Explain how the astrometric technique differs from the Doppler wobble technique. Also, name and briefly explain the two major difficulties (different from Doppler wobble difficulties) that have caused this technique to only be of limited use so far.

The astrometric technique for detecting extrasolar planets uses very precise measurements of stellar positions in the sky to look for the stellar motion caused by orbiting planets. In this way, astronomers can measure the side-to-side angular distance between a planet and its star. The astrometric technique looks for side-to-side motion, while the Doppler wobble technique looks for back-and-forth motion. Two major difficulties that have caused this technique to only be of limited use so far are... - the farther away a star is, the smaller its side-to-side movement will appear. This method therefore works best for detecting the gravitational effects of massive planets around relatively nearby stars. - For a planet of any particular mass, a greater orbital distance means a larger atmospheric effect on its star, but it also means that the effect takes longer to measure.

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.

Explain author Michael Shermer's two arguments regarding why any contact with extraterrestrial intelligence (ETI) will likely be benign.

The author mentions that our world has become less and less explorative. Thus, other civilizations will not be exploring for us. And he also mentions that it would not be worth it for other civilizations to spend the years and years necessary for interstellar space travel.

Briefly explain the capture hypothesis for the origin of the solar system. Name and briefly explain three arguments that tend to contradict this hypothesis.

The capture hypothesis for the origin of the solar system is that the sun and planets all formed independently. And after the sun formed, its gravity captured passing planets. Three arguments that contradict this hypothesis are... - Space is too big, encounters are unlikely - Capture of the planets by the suns orbit is physically difficult because of the escape velocity. To capture a planet there needs to be a way to slow it down. - The orbits of the planets would be random.

What recent evidence discovered in Antarctica implies that life may have once existed on Mars?

They discovered meteoroids in Antarctica that match up with the surface of Mars. They were hoping to find some kind of fossils inside the rocks.

Explore the following web site from NASA's Goddard Space Flight Center about the Martian meteorites:http://rsd.gsfc.nasa.gov/marslife/marsmet/. Based on the information found here, answer the following: What conclusive evidence shows that these meteorites are from Mars? Why aren't these meteorites red like the Martian surface soil?

The conclusive evidence that the SNC meteorites originated on Mars comes from the measurement of gases trapped in one meteorite's interior. The trapped gases match those that Viking mission measured in the Martian atmosphere. The oxidized iron produced by weathering in surface rocks gives Mars its red color, but the less-weathered igneous rocks just below the surface are gray or black (like these samples).

Explain the two major (gravity-related) heat sources that made the early, forming Earth so hot that it was completely molten throughout. What is the current heat source that keeps Earth's interior partially molten?

The early-forming Earth was heated by impacts and differentiation. The impacts of meteoroids and other objects generated heat as they hit the surface of the earth. Differentiation of the Earth led to nuclear fusion in the core, which in turn created heat. Earth's interior is still partially molten today because of the radioactive decay occurring within the core.

Know the rules of Doppler shifting. Be able to explain with a simple diagram the difference between radial and transverse velocity.

The first rule of Doppler shifting is objects moving toward you are blueshifted (shorter wavelength, higher frequency), while objects moving away from you redshifted (longer wavelength). The second rule of Doppler shifting is that the amount of shift is proportional to radical velocity along the line-of-sight. Radical velocity is in line with the line-of-sight, and transverse velocity is perpendicular to the line-of-sight.

Explain how the Earth's rotation, combined with the tidal bulges from the Moon, result in the Moon's orbital distance from the Earth slowly increasing over time. Diagram would really help here.

The gravitational pull of the bulges creates a net force that adds energy to the moon's orbit, and pulls it slightly ahead in its orbit. This causes the moon to move gradually away from the Earth.

hat is a half-life? Be able to work your way through a simple example like we did in class to determine the age of something. For example, if we know the original composition of an object was 1.2% Carbon-14, the current composition is 0.15% Carbon-14, and the half-life of Carbon-14 is 6000 years, what is the age of the object?

The half-life of a substance is the amount of time it takes for half of that substance to decay.

Explain how we can use ice core measurements to estimate the Carbon Dioxide content of the atmosphere hundreds of thousands of years ago. How do current atmospheric conditions compare to those measured during the past 400,000 years?

The ice cores have small air bubbles that can be analyzed to estimate the content of Carbon Dioxide hundreds or thousands of years ago. They find different organisms in the bubbles and can determine the temperature at the time from that because different organisms are present at different temperatures. Looking at these ice cores scientists have found that the CO2 levels in the atmosphere are much higher than they were 400,000 years ago.

On the 5-km highway of time representing the history of Earth, what length accurately reflects all of recorded human history?

The last few millimeters on a 5-kilometer highway of time representing the history of the earth reflects all of recorded human history. Each kilometer equals 1 million years.

In the reading "Philosophy and the Scientific Method," a "letter to the editor" is discussed, in which the letter writer confuses correlation and causation. Explain the difference between the letter writer's point of view and the scientific point of view.

The letter writer just looked at two facts, that sex ed. is normal is schools today, and that teen pregnancy has increased. From these to facts he saw a possible correlation and assumed that the sex ed. is the cause of this increase in teen pregnancy. However for the scientist he wanted to look more into it. What for most people is the conclusion of an investigation is only the beginning of an investigation for a scientist. The scientist thought of other things such as, the increase in the population of teenagers, or the accessibility to inappropriate music and TV shows. Correlation does not prove causation. Even though there may be a correlation, there could be other factors that are the real cause to the situation.

What evidence in our atmosphere suggests that the recent warming of the past century is not due to changes in solar activity?

The levels of Carbon Dioxide, Methane, and Nitrous Oxide in our atmosphere have dramatically increased since the past, which are all greenhouse gases, and are warming the planet.

How and why does the lifetime of a civilization relate to the probability that we are not alone?

The longer a civilization lasts, the more likely it is for us to overlap with another civilizations' existence and lifetime.

Briefly describe how the appearance of both the lunar maria and the highlands. Explain how the maria of the Moon formed and why their appearance differs from that of the lunar highlands.

The lunar maria are areas of the moon where lava from an internal heat burst into the lower impact basins and renewed the surface - (darker, flatter, and relatively smooth). The lunar highlands are areas of the moon that are ancient and have not been renewed - (higher, brighter, rocky, and heavily cratered). The highlands tell us that heavy bombardment occurred early in the solar system's history, before the maria filled some of the basins.

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.

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.

The moon maintains a record because the highlands have not been renewed and are the same as they were even in the earliest stages of the moon. The lack of geological activity has allowed the moon to preserve ancient impacts. Radiometric dating of rocks from the moon tell us that heavy bombardment occurred early in the solar systems history and ended about 4 billion years ago. The earth, however, has since renewed its surface since the times of early bombardment. It has done through weathering and plate tectonics.

From section 10.6, describe the negative feedback loops that have kept Earth's climate from becoming too warm or too cold in the past. Why are these feedback loops likely not sufficient to stabilize Earth's climate if we triple the Carbon abundance in our atmosphere over the course of the next 100 years?

The negative feedback loops that have kept Earth's climate from becoming too warm or too cold in the past work like this... - If the earth cools down a little precipitation decreases, so less CO2 is dissolved in rainwater, allowing the CO2 to be released through volcanoes, increasing the CO2 in the atmosphere. The increase in CO2 concentration causes the greenhouse effect to occur, which warms the earth. - If the earth warms up a little precipitation increases, so more CO2 is dissolved in rainwater, which causes the amount of CO2 in the atmosphere to decrease. This weakens the greenhouse effect, so the earth cools down. These feedback loops are likely not sufficient to stabilize Earth's climate if we triple the Carbon abundance in our atmosphere over the course of the next 100 years because it takes hundreds of thousands of years for atmospheric CO2 to stabilize through the CO2 cycle.

Why are craters on Mercury typically larger than craters found on the Earth's Moon?

The objects striking Mercury most likely had a higher velocity, which would cause their impacts to create larger craters. If they were moving in elliptical orbits around the sun, the projectiles would have been moving faster in the region of Mercury's orbit than if they were farther out.

From chapter 8.3 in your textbook, your book discusses how we can use our understanding of geological and chemical processes to deduce the original composition of a rock for the purposes of radioactive (or radiometric) dating. One example discussed in the book is with potassium and argon. Explain how we know that the original abundance of Argon 40 in a rock is zero and how we know no Argon 40 has escaped from the rock.

The parent isotope of Argon 40 is Potassium 40, which means that Potassium 40 is the original isotope before decay and Argon 40 is left behind by the decay process. By knowing that the radioactive Potassium 40 can decay into Argon 40 by the end of its half-life, then we can conclude that there was no Argon in the original abundance. So by knowing the decay process of Potassium 40, that it will turn into Argon 40 every half life, we can conclude that Argon was never lost because it was not the original isotope and in fact it is being created.

From chapter 5.4, explain how we can use spectral absorption (or emission) lines to uniquely determine the composition of an interstellar gas cloud or distant planetary atmosphere.

The patterns & wavelength of lines are different for each element, giving each element a unique spectral fingerprint. Each type of atom has its own unique set of energy levels and the ions of an element produce fingerprints that are different than neutral atoms.

From the reading "Philosophy and the Scientific Method," (below the syllabus links on the main class web page) what is the primary difference between a scientific and a non-scientific belief? What is the major weakness of using irrefutable beliefs as a basis for a system of knowledge? I strongly recommend you check your answer on this one with me.

The primary difference between scientific and non-scientific beliefs is that non-scientific beliefs are irrefutable. They are unable to be proved wrong; where as scientific beliefs can be proved wrong. Scientific beliefs are based off facts and statistics and can be proved wrong with research. The problem with irrefutable ideas is that it is hard to prove them wrong. However when one irrefutable belief contradicts another, there is no decisive way to choose between them. With an irrefutable belief all we have left is a "maybe-belief", there is not 100% certainty or facts.

Describe how written records can be used to estimate the temperature from hundreds of years ago, even before the invention of the thermometer.

The records people would write years ago before thermometers would say when flowers would first bloom, and when lakes would freeze. Scientists are able to analyze this data to determine the climate back then and compare it to now.

According to the fossil fuel industry, increases in Carbon Dioxide will act like "plant food" and accelerate the growth of forests and other plant life. Explain how this hypothesis is being tested and whether the test confirms the hypothesis.

They are experimenting on a forest by putting 500 ppm of CO2 into the forest to see how it will be after 50 years. 2 years into the experiment they found a 25% increase in the growth of the plants/trees in the forest.

Explain why the large, roughly spherical solar nebula collapsed into a disk shape rather than just a smaller sphere.

The roughly spherical nebula has a spin to it, which causes it to have a centripetal force going horizontally across the center of the nebula pushing outward. When the gravity is pushing on the solar nebula equally around the sphere the centripetal force pushes back and is not collapsed there, causing the solar nebula to collapse into a disk shape rather than just a smaller sphere.

From chapter 8.3 of your textbook, briefly describe the evidence in meteorites (related to Xenon gas) that support the idea that the collapse of our solar nebula initially was caused by a supernova explosion.

The solar nebula could not have started collapsing on its own because gravity is too weak. Scientists suspected that there was some cataclysmic event that triggered the collapse. Some meteoroids contain the isotope xenon-129. Xenon is gaseous even at extremely low temperatures, so it could not have condensed and become trapped in the meteoroids as they condensed in the solar nebula. The Xenon-129 we observe in meteoroids today is the product of radioactive decay of iodine-129 produced in a supernova that occurred no more than a few tens of millions of years before the collapse of the solar nebula began. The relatively short time period between a supernova and the birth of out solar system suggests that a shock wave from the exploding star may have been the trigger for the nebulas collapse. Once this shock wave got the collapse started, gravity took over and made the rest of the collapse inevitable.

What evidence on the surface of Mars indicates Mars has little significant internal heat? Explain.

The surface of Mars is covered with old craters. There has been very little recent geological activity and basically no surface renewal. It has remained relatively unchanged.

Explain why planetary scientists, prior to the Huygens encounter with Titan, believed that Titan may have a methane cycle similar to the water cycle we have here on Earth.

The surface temperature of Titan was close to the triple point of methane, just as the Earth's is close to water, and at this temperature gas, colds, and liquids can coexist.

From chapter 8.2 of your textbook, explain why the temperature of the solar nebula increased as the cloud collapsed. Also explain why the initially slowly spinning cloud (especially the central, densest part - the protosun) spun faster as the cloud collapsed.

The temperature of the solar nebula increased as the cloud collapsed because as the cloud shrank, its gravitational potential energy was converted to the kinetic energy of individual gas particles falling inward. These particles crashed into one another, converting the kinetic energy of their inward fall to the random motions of thermal energy. These random motions of thermal energy are what increased the temperature in the center and formed the Sun. The initially slow spinning cloud spun faster as the cloud collapsed because it was shrinking in radius. The increase in rotation rate represents conservation of angular momentum in action, where the greater the angular momentum of rotation cloud, the more spread out it will be. So a smaller size means a faster rotation.

From section 10.6, explain the evidence offered by the textbook's authors (related to computer models) that suggest the recent warming of the Earth has been caused by human activity rather than some natural cycle.

The textbook author evidence that the recent warming of the Earth is caused by human activity is that... - The increase is greenhouse gases are a clear reason of warming, and our burning of fossil fuels and other human activities is a main cause of the increase of greenhouse gases. We know the increase is because of fossil fuels and not natural sources because of the isotopes present in our atmosphere correspond with the isotopes in fossil fuels. - Also, climate models that ignore human activity do match the observed rise in temperature that our world is actually experiencing.

From chapter 5.3 in your textbook, state the three different ways that atoms contain energy. What does "energy level" mean in the context of electrons in an atom?

The three different ways that atoms contain energy are... - By virtue of their mass, they possess mass-energy in the amount of mc2. - They possess kinetic energy by virtue of their motion. - And they contain electrical potential energy that depends on the arrangement of their electrons around their nuclei. Energy Level is the specific possible energies of an atom. In the context of electrons ????? Only charged particles can interact with light so when dealing with energy levels, an electron can only change levels if it gains or loses the amount of energy separating the levels. If an electron gains enough energy to reach the ionization level, it will escape the atom, leaving a positively charged ion.

What are the three ingredients necessary for life? What is a possible source for each ingredient?

The three ingredients necessary for life are energy, water, and organic molecules. A possible source for water and organic molecules is molecular clouds. A possible source for energy is the sun.

What causes the Earth's tidal bulges to "lead" the Moon in its orbit? Describe this and be able to draw a simple diagram explaining this effect. How and why does this affect the rotation speed of the Earth over time?

The tidal bulges want to point at the moon, but the rotation of the Earth won't allow it. The friction created by the tidal forces pulls the tidal bulges ahead of the moon. At the same time, the moon's gravity tries to pull the bulges back in line with itself, slowing the earth's rotation.

Suppose we see a star wobbling back and forth and can measure its Doppler shift changing over time. What two properties of the star's companion planet can we deduce from this information? Explain briefly how each is deduced.

The two properties of the star's companion planet that we can deduce from this information are the mass, and the orbital period. The star's companion planets mass is deduced by using the Doppler shift changing over time to find the radial velocity, because they are proportional. The planets radial velocity can be used to find the orbital velocity and in turn its mass. The greater the star's velocity, the greater the mass of the companion planet that is influencing the star's wobble. The Orbital Period is deduced by using the sinusoidal pattern of the radical velocity vs. time graph.

Name and briefly explain the significance of two important differences between Venus and Earth that led Venus to undergo the Runaway Greenhouse process while Earth did not.

The water on Venus is more vulnerable than of that on Earth. This is because it is affected by solar wind stripping and UV break up, two things that the Earth is not affected by. Because Venus does not have a magnetic field or an ozone layer, solar wind and UV light breaks apart the water molecules in its atmosphere.

How do we know that water has been present on the Earth since shortly after its formation?

There are crystals of zirconium silicate, called zircons, that formed 4.4 billion years ago and whose oxygen isotopic composition indicates that liquid water was present then. So water has been on Earth's surface throughout most of its history.

One alternative source of power that may help account for current energy production and future growth is nuclear energy. What are two major long-term drawbacks associated with nuclear energy?

There is not enough uranium in the earths crust to supply the amount of energy our world uses. We could run out in about 10 years. They don't know how to properly and safely dispose of the waste (fuel rods).

From Chapter 4, section 4.3 of your textbook, briefly explain the difference between thermal energy and temperature. Explain why can you safely put your arm in a 400-degree oven (for a brief time) but you cannot do the same for a pot of (212 degree) boiling water.

Thermal Energy measures the total kinetic energy of all the randomly moving particles in a substance (energy in the form of heat). Temperature measures the average kinetic energy of the particles. Because the pot has a higher density than the oven. Since the pot has a higher density there are more molecules in the same amount of space, so many more molecules strike your arm in one second in the pot than in the oven. More molecules hitting your arm means more Thermal Energy being transferred into your arm.

List or briefly describe five ways that gases can leave a planet's atmosphere.

Thermal Escape - gas reaches escape velocity Solar Wind Stripping - wind sweeps particles into space Condensation - gas condenses and falls as perspiration, returns gas to surface Chemical reactions with surface materials - rusting, gas becomes part of metal Large impacts can blast atmospheric gases into space

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, or asteroids. 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.

Explain why the Earth has two tidal bulges as a result of the Moon's gravity.

They are caused by a difference in gravitational pull. The difference in the gravitational attraction between near side and far side tries to pull the Earth apart, resulting in tidal bulges both toward and away from the moon. When you pull on a rubber band from only one side, it still stretches in both directions.

Explain why nuclear fusion reactions require extremely high temperatures. Also, why must the fusing material be contained somehow?

They require high temperatures to get the two atoms close enough together to fuse. They must be contained so it is easier to get them close to each other.

From chapter 4.5 of your book, answer the following: The same face (side) of the Moon always points at the Earth. We call this phenomenon "tidal locking" or "synchronous rotation". Explain why this occurs.

This phenomenon is a natural consequence of tidal friction. The Earth's tidal force on the moon is much greater than the moon's tidal force on the Earth because the Earth is so much more massive. This created friction, which over many years caused the moons rotational to slow down until the point that its bulges were synchronized with its rotation. Once this happened, there was no longer a source for tidal friction.

Briefly describe each of the three properties of a planet that determine its temperature. Use these to help explain how we know that the greenhouse effect is real and warms the Earth by about 60 degrees Fahrenheit.

Three properties of a planet that determine its temperature: Distance from the Sun, Albedo (reflectivity; meaning the % of reflected light. Higher Albedo, the cooler the planet), and Greenhouse Effect. The earth is slightly more reflective than the moon though (30% vs. 6%). So because of that the earth should be cooler, however because of the greenhouse effect the moons average temp. is 0 degrees, and the earths is 60 degrees.

What are three types of renewable power sources mentioned in the film? Briefly explain two major drawbacks that are associated with renewable energy sources in general.

Three types of renewable power sources are Solar Power, Biomass, and Wind Energy. Renewable energy sources are not always there when you need them, and they have a low power density; you need a large amount of land to get the energy.

From Chapter 12.4, first summarize the argument made in the book that the presence of jovian planets in our solar system has made it easier for life to exist on the Earth. Second, summarize the argument that even though Jupiter may have made it easier for life to exist on Earth, it also slowed down the evolutionary process.

Ultimately, every asteroid or comet that has impacted the Earth since the end of heavy bombardment was in some sense been sent our way by the influence of the jovian planets. Therefore, there is a connection between the jovian planets and the survival of life on Earth. Without Jupiter, the threat from asteroids might be much smaller but the threat from comets might be much greater. Without Jupiter, those comets may have remained dangerously close to Earth. Some scientists argue that more impacts would have damaged life on Earth while others argue that more impacts might have paved the way for our existence and sped up evolution.

Why doesn't Venus have a magnetic field? Explain.

Venus doesn't have a magnetic field because it does not rotate.

Although Venus started with an atmosphere that was probably very similar in mass and composition compared with the Earth, various differences between Earth and Venus led to a gradual loss of water vapor on Venus, combined with an enormous increase in the carbon dioxide content. Describe the positive feedback mechanism (Runaway Greenhouse Effect) by which water is lost and the atmosphere thickened.

Venus is warmer than the Earth, so it has more water vaporization. Venus also loses water vapor from solar wind stripping and UV radiation. Less water causes fewer CO2 sinks and CO2 continues to build-up increasing the greenhouse effect.

Explain the properties of the surface of Venus leads us to the conclusion that (a) the solidification age of the surface is about 500 million years old (about 5x that of Earth's surface) and (b) that at that time 500 million years ago, Venus probably suffered some sort of sudden event that caused the whole planet to melt and the whole surface to reset itself.

Venus's crater density is about 5x Earth's crater density, and Earth's average solidification age is about 100 million years. This helps us conclude that the solidification age of the surface of Venus is about 500 million years old. The craters on Venus's surface are pristine - there are no gradual mechanisms to erase craters on Venus. Also the craters are distributed uniformly. Based off this we can conclude that something erased craters 500 million years ago, probably quickly and globally.

What does it mean to say that we are communicating with extraterrestrials already? What do our signals sound like at various distances from the Earth? Explain.

We are communicating with them because we are broadcasting TV and radio signals. The further you get from the Earth, the older the signals you will hear. For example, the radio waves about 50 light years away are from 1961. If you get far enough out you will not hear anything because we have only been broadcasting for less than 100 years. This is because the speed of the broadcast.

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 shift always tends to underestimate the planets mass, so the estimated mass is always under the true mass.

Note that we cannot use Argon reconstruction as a way of estimating the mass of the original Martian atmosphere. Why not?

We cannot use Argon reconstruction because the lighter argon isotope found on Mars, Argon 36, has been depleted. Therefore we cannot compare. We have discovered this by observing Mar's isotope fingerprint.

If Venus had twice as much Argon today as the Earth, what would we then assume about Venus' original atmosphere? Explain.

We would assume that Venus' original atmosphere contained twice as much Argon, meaning that it also had twice as much of all the other gases in it's original atmosphere. Venus' original atmosphere would have been twice as heavy as Earth's.

Explain the difference between weather and climate. Why is local temperature variation not really important in terms of global warming?

Weather is a local, short-term measurement; while climate is a global, long term measurement. The variation in local temperatures is not significant because global warming is determined by the change in global average temperatures over an extended period of time.

Explain how underground caverns can store and release energy generated by windmills. Also, explain one technical hurdle in this process and how utilities are trying to overcome it.

When electricity supply exceeds demand powerful electric pumps inject air at high pressure into a cavern located underground. When the grid is running short, some of the compressed air is let out, blasting through the turbines and spinning them to generate electricity. One technical hurdle of this is that air heats up with it is compressed and gets cold when it is allowed to expand. So some of the energy that goes into compression is lost as waste heat.

From chapter 5.4, In a gas showing absorption lines, the lines in the spectrum occur when electrons absorb light and move to higher energy levels. But these same electrons will quickly return to lower levels, emitting exactly the same photon energies in the process. Why don't these two effects cancel out, leading to no net change in the original light?

When the electron returns to its original level, emitting a photon of the same energy as the one absorbed, this is what causes an absorption line. If the two effects canceled out, than there would be no absorption lines because there wouldn't be any electrons emitting photons when they return to their original level.

In addition to an increase in CO2 due to volcanic eruptions, describe two other processes that contributed methane and CO2 to the atmosphere to accelerate the warming process during the PETM era.

Wildfires/the buying of decayed or living organisms. Permafrost defrosts microbes consume thawing remains and burp up methane.

Would we still have high tides and low tides if we had no moon? Explain.

Yes, the sun still would produce tides, they would just have a low amplitude.