AST 101 Essay Study Guide

3. Suppose you were in charge of developing and prioritizing future planetary missions for NASA. What would you choose as your first priority for a new mission, and why? In addition, politician often argue over whether planetary missions are worth the expense involved. Based on what you have learned by comparing geologies of the terrestrial worlds, do you think the missions have given people this knowledge have been worth their expense?

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2. Every so often, someone claims to have built a machine that can generate energy perpetually from nothing. Why isn't this possible according to the known laws of nature? Why do you think claims of perpetual motion machines sometimes receive substantial media attention?

1. The law of conservation of energy says that the amount of energy is constant. Therefore if you have some, it came from somewhere. It couldn't have been generated out of "nothing". 2. The law of entropy says that, left to themselves, a systems will move from a more ordered state to a less ordered state. Applied here, that means that the machine has friction, wear and other problems and will eventually run down. They receive media attention because, unfortunately, people are scientifically illiterate. Therefore they accept junk science easier.

2. Daily information about solar activity is available at numerous websites. Where is the earth in the sunspot cycle right now? When is the next solar maximum or minimum expected? Have there been any major solar storms in the past few months? If so, did they have any significant effects of Earth? Include in your response the processes behind the sunspot cycle.

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2. Politicians often argue over whether planetary missions are worth the expense involved. Based on what you have learned by comparing the geologies of the terrestrial worlds, do you think the missions that have given people this knowledge have been worth their expense?

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2. Suppose the impact 65 million years ago had not occurred. How do you think Earth would be different? For example, do you think that mammals still would eventually have come to dominate Earth? Would people be here? In addition, based on your own opinion of how impacts threaten Earth, how much money and resources do you think should be used to alleviate it? What types of programs would you support? (Examples include program to search for objects that could strike Earth, to develop defenses against impacts or to build actual defenses.)

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3. Suppose you could choose any one moon to visit in the solar system. Which one would you pick, and why? What dangers would you face in your visit to this moon? What kinds of scientific instruments would you want to bring along for studies? What is the goal of your visit?

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5. Many of the newly discovered planets orbiting other stars are more massive than Jupiter but orbit much closer to their stars. Assuming that they would be Jupiter-like if they orbited at a greater distance from their stars, how would you expect these new planets to differ from the Jovian planets of this solar system? How would you expect their moons to differ?

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1. Scientists have found that much of a planet's geological history is destined from its birth. Briefly explain why, and discuss the level of detail that is predictable. For example, was Mars' general level of volcanism predictable? Could science have predicted a mountain as tall as Olympus Mons or a canyon as long as Valles Marineris?

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2. Considering the overall process of solar system formation, do you think it was likely for a planet like Earth to have formed? Could random events in the early history of the solar system have prevented Earth from being here today? What implications do your answers have for the possibility of Earth-like planets around other stars? Take into account the climate histories of Venus and Mars, as they make it clear that it is not easy to get a pleasant climate like that of Earth. How does this affect your opinion about whether Earth-like planets might exist around other stars?

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1. The modern world is filled with ideas, knowledge, and technology that developed through science and application of the scientific method. Discuss some of these things and how they affect your life. Which of these impacts do you think are positive? Which are negative? Overall, do you think the human race has benefited from science?

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5. Suppose you observe a sunspot from Earth, taking a picture of the Sun each day. Using these photos, you measure the time it takes for the sunspot to return to the position it had in the first picture. Now suppose a friend of yours standing on Pluto does the same thing. Would you and your friend measure the same time for the sunspot to return to where it started? Explain your answer.

First of all, you'd have to take into account the speed of light. Light will reach Earth faster than light will reach Pluto. Also, you'd have to take into account the orbital rotation of the planet that you were standing on while observing the sunspots on the sun. And finally, you'd have to take into account the orbital speed of the planet on which you were on (because speed affects your perception of time: theory of relativity). If you indeed did take these two things into account, then yes, I believe that someone on earth and someone on pluto would measure the same time. However, if you failed to take into account one of these things, then you and your friend on pluto would observe different times.

5. Technological innovation clearly drives scientific discovery in astronomy, but the reverse is also true. For example, Newton made his discoveries in part because he wanted to explain the motions of the planets, but his discoveries have had far-reaching effects on civilization. Congress often must decide between funding programs with purely scientific purposes ("basic research") and funding programs designed to develop new technologies. If you were a member of Congress, how would you try to allocate spending for basic research and technology?

I believe research has a higher importance than new technology. As a member of Congress I'd choose research over developing new technology. The reason I'd do this is simply because I believe we have a surplus of technological advances that lack the research to unlock their full potential. There's plenty of existing inventions that we haven't reached the limits on. When it comes to Astronomy there's plenty of technology and we're not even close to pushing this technology to the limits because we haven't put the time and research in. If I had the funding to split on both I'd likely go 70% to research and 30% to new technology. I would adjust this depending on the advances in research made over time. I've never really gave much thought about the relationship between new technology and research until now. I think about how far we've come with technology and its pretty mind boggling. However, we're still finding new ways to use this technology thanks to research.

4. A Time magazine cover once suggested that an "angry Sun" is becoming more active as human activity is changing Earth's climate through global warming. It's certainly possible for the Sun to become more active at the same time that humans are affecting Earth, but it is possible that the Sun could be responding to human activity? Can humans affect the Sun in any significant way?

I believe the Sun is becoming more active rather than humans having any significant impact on it. I believe people are pointing fingers at the Sun and blaming it for increased temperatures. However, the human race can take the majority of the blame for this. I'd actually refer to the Earth as "angry" before the Sun. I doubt there would be any significant impact directly from the Sun if we subtracted the human race from the equation. We're the direct cause of global warming and any major climate changes. There'd absolutely be changes without humans. However, it'd be nowhere near the negative impact that we've made. The pollution and the increase in temperature are causing our environment to be angry, not the Sun.

1. What is the significance of the discovery of extrasolar planets, if any? Next, use the internet to find the latest information on extrasolar planet discoveries, include for each planet the technology used to detect the planet, any information about the nature of the planet and discuss how the planet does or does not fit in with current understanding of planetary systems. Lastly, have any extrasolar planets been detected that are similar to Earth?

I believe the significance of these planets is that they're possible places to support life. Also, the exploration and discovery of the planets lead to major technological advances such as digital cameras. Extrasolar planets have been discovered that are Earth-like. An example of this would be Kepler-62e. This was discovered using the transit method. This is where you observe for a reduction of light where a planet passes in front of a star.

5. Consider Earth's size and distance from the Sun. Choose one property and suppose that it had been different (for example, smaller size or greater distance). Using scientific principles you have learned in this class, describe how this chance might have affected Earth's subsequent history and the possibility of life on Earth.

I chose to imagine the Earth closer to the Sun and how this would affect life. The first thing we'd obviously notice is the increased temperature. I'm sure it'd make places like Arizona impossible to live in. A small change in temperature would likely melt large masses of ice around the world. This would flood a large amount of land if not all. The increased heat would cause CO2 to be released from our oceans, which would cause an additional heat rise. The original rise in temperature would only continue to be amplified by its own affects on the planet. I believe if we were closer to the Sun, life wouldn't be possible. We'd either be drowning in water or melting in the Sun. The perfect conditions were required to support life on this planet. If anything major changed in the composition or position of the planet, there'd be drastic changes.

2. Why was astronomy important to people in ancient times? Discuss both the practical importance of astronomy and the importance it may have had for religions or other traditions. Which do you think was more important in the development of ancient astronomy, its practical or it philosophical role?

I think astronomy was so important to them because it was something constant and 100% predictable. I think at first they realized it was great for keeping time, then they saw it was good for locations/directions. The constellations were in the same place the same times of the year. Obviously, astrology came from Sun worship..etc since the beginning of time.

4. Suppose the solar wind had cleared away the solar nebula before the seeds of the Jovian planets could gravitationally draw in hydrogen and helium gas. How would the planets of the outer solar system be different? Would they still have many moons?

I would assume that, if the gas giants lacked their massive gaseous atmospheres, they wouldn't have nearly as many moons as they do now due to the huge mass loss that'd result. Less mass = less gravitational pull = less ability to hold moons in orbit.

1. In 1835, French philosopher Auguste Comte stated that science would never allow people to learn the composition of stars. Although spectral lines had been seen in the Sun's spectrum by that time, it wasn't until the mid-1800's that scientists recognized that spectral lines give clear information about chemical composition (primarily though the work of Foucault and Kirchhoff). Why might your present knowledge have seemed unattainable in 1835? Discuss how new discoveries can change the apparent limitations of science, such as the question of how life began on Earth. Do you think such questions will ever be answerable through science?

In 1835 the time hadn't been spent on determining what the stars were composed of. It wasn't until Joseph Lockyer studied the spectra of solar prominences in eclipses. The process of discovery hadn't taken place. This was a series of events leading to this discovery. Discoveries in science is like opening a door and discovering 10 additional doors. We've broken truths in half countless times in the past and we'll continue to do so. I believe there's and answer to everything and only time will tell when we'll find it.

3. Some people have suggested that it might be possible to carry out planetwide engineering of Mars that would cause the climate to warm and its atmosphere to thicken. This type of planet engineering is called terraforming, because its objective is to make a planet more Earth-like and therefore easier for humans to live on. Using scientific principles you have learned in this class, discuss what steps you would take to terraform Mars.

Mars has many similarities to earth so it's no surprise to see so much interest in potentially living on Mars. The fact that Mars was once even more similar to Earth than it is now, makes it a prime target to support life. Terraforming is an interesting concept but I'm not sure we're quite there with technology to do so. That's not to say we can't work towards this as technology advances. I believe in order to terraform Mars we'd have to start with giving the core a jump-start. This would bring back the original magnetosphere it once had. The magnetosphere would make the planet capable of holding onto its atmosphere. Without this magnetic pull, the solar winds will strip any atmosphere away from the planet. I'm not sure how we'd jump the core but that's not to say it's impossible. We'd have to be careful in the method used to do so as it'd have to be something of great power. This would be a major task and all consequences would have to be examined prior to completion. Holding an atmosphere in is the foundation, as efforts would be wasted without a solution. The next step I'd take in terraforming Mars would be to build factories that would pump greenhouse gasses into the atmosphere. This heat would cause the polar ice caps (frozen CO2) of Mars to turn into vapor. This would release for CO2 gas that would capture more heat from the Sun. This would create additional greenhouse gasses. In my final steps I'd complete the atmosphere my introducing organisms to build and ozone layer. Without this this layer life would be exposed to harmful ultraviolet radiation from the Sun. I'd also heat the soil and release the nitrogen within. In recent events NASA's rover discovered nitrogen compounds within the soil when heated. If we could find a way to release tons of nitrogen, then we'd have our basic atmosphere complete. Again, I don't believe we're any where near terraforming Mars but it's interesting think about the possibilities if we could.

3. The ocean tides on Earth are much more complicated than they might at first seem from the simple physics that underlies tides. Discuss some of the factors that make the real tides so complicated and how these factors affect the tides. Consider the following factors: the distribution of land and oceans, the moon's varying distance from Earth in its orbit, and the fact that the moon's orbital plane is not perfectly aligned with the ecliptic and neither the moon's orbit nor the ecliptic is aligned with Earth's equator.

Most people look at the ocean and give very little thought to physics taking place within it. The main factors that make up tides are the Moon, Earth, and Sun. The Moon and Earth play the largest role in tides. Tides affect both the land and the ocean. We only notice the ocean because water flows more than land. The ocean is pulled toward the moon on the side facing the Earth creating a bulge. The land on the opposite side of the Earth is pulled toward the Moon and this causes a bulge. These are the high tides on opposing sides of the Earth. The other sides of the earth are at low tide during this point due to being stretched thin from the bulges. These bulges cause tidal friction which is where the Moon's gravity tries to keep the tidal bulges on the Earth-Moon line while the Earth tries to keep rotating with those bulges. This friction slows down the Earth's rotation. Also, the gravity of the bulges pulls the Moon ahead in its orbit, causing the Moon to move farther away from Earth. This causes longer days over a long enough period of time. The Sun's role is that it increases high tides and reduces high tides. When the Sun and Moon are in alignment, the gravitational pull increases causing spring tides. When the Sun and Moon are at right angles from one another, the gravitational pull decreases causing neap tides. I'm guilty of not giving much thought to what causes high and low tides. The ocean is quite a site to take in on its own let alone considering what's going on within it. The various factors that play into tides are far more complex than I would've guessed. I didn't have any idea that the Moon is slowly moving farther away from Earth. I look forward to sharing this information with the next person to ask me about the factors involved with tides.

5. Write an executive summary of the major roles that Copernicus, Tycho Brahe, Kepler and Galileo played in overturning the ancient belief in an Earth-centered universe.

Nicholas Copernicus (1473-1543) • Based his work off of the heliocentric (sun-centered) ideas of Aristarchus (c. 260 BC) • Was able to order planets around the Sun and easily explain the perplexing retrograde motion of some planets • Held fast to circular orbits and included nearly as many epicycles as the Ptolemaic model • Didn't convince many people because his model was no more accurate than the Ptolemaic model Tycho Brahe (1546-1601) • Observed a supernova in 1572 and showed it was a "new star" that had changed the "perfect" sky • Observed a comet in 1577 and proved by parallax measurements that it was not a feature of Earth's atmosphere • Founded a (pre-telescopic) observatory where he spent ~30 years measuring the positions of planets to 1 arcminute accuracy Johannes Kepler (1571-1630) • Hired by Tycho to analyze the large data set he had collected • Worked diligently on a model with circular orbits, but was never able to match it perfectly to Tycho's accurate data • Finally threw out the canonical circular orbits and ended up developing a much more accurate system using elliptical orbits • Kepler's model is described by his three laws which place the planets in different sized elliptical orbits with the sun at a focus Galileo Galilei (1564-1642) • Used the newly-developed telescope to overcome three important and long-held beliefs that would have made a heliocentric model impossible o Belief 1: If Earth were moving, objects in the air would be left behind. • Galileo used experiments to show how objects in motion will stay in motion (an early form of Newton's first law), so objects in Earth's atmosphere could conceivably continue to move with the planet o Belief 2: The heavens must be perfect and unchanging. • With his telescope, Galileo observed the Sun and moon. He found sunspots (imperfections!) on the Sun and observed mountains (more imperfections!) on the moon. o Belief 3: If Earth orbits the Sun, then we should see stellar parallax. • Galileo was able to resolve the band of the Milky Way into individual stars in his telescope, giving evidence that the stars were far more distant than most people had believed. • Additionally, Galileo observed several moons around Jupiter, showing it was very possible for objects to orbit something other than the Earth. • Galileo's most conclusive observations were that Venus goes through phases similar to those of the moon. It also changes size considerably during its phase cycle, something which can only be explained by a heliocentric solar system. Being contrary to the geocentric model, these observations falsified the theory of Aristotle and Ptolemy. Isaac Newton (1642-1727) • Created calculus to allow for the mathematical description of many physical processes • Recorded three laws of motion that helped to fill in understanding of the physical world • Developed a universal law of gravitation which governs the motions of all bodies with mass • Newton's work demonstrated why the planets of the solar system acted as Kepler had described

2. Suppose that all the raisins in a cake are one centimeter apart before baking and four centimeters apart after baking. Describe qualitatively how the cake looks before and after baking; pay particular attention to the distance between raisins. Suppose you identify one raisin as the Local Raisin; qualitatively describe the distances and speeds of other raisins as seen from the Local Raisin. Lastly, compare how the expanding cake is similar to the expansion of the universe.

Notice, for example, that Raisin 1 starts out at a distance of 1 centimeter before baking and ends up at a distance of 3 centimeters after baking, which means it moves a distance of 2 centimeters away from the Local Raisin during the hour of baking. Hence, its speed as seen from the Local Raisin is 2 centimeters per hour. Raisin 2 moves from a distance of 2 centimeters before baking to a distance of 6 centimeters after baking, which means it moves a distance of 4 centimeters away from the Local Raisin during the hour. Hence, its speed is 4 centimeters per hour, or twice as fast as the speed of Raisin 1. Generalizing, the fact that the cake is expanding means that all the raisins are moving away from the Local Raisin, with more distant raisins moving away faster.

5. Believe it or not, there is an organization called the Flat Earth Society. Its members hold that Earth is flat and that all indications to the contrary (such as pictures of Earth from space) are fabrications made as part of a conspiracy to hide the truth from the public. Discuss the evidence for a round Earth and how you can check it for yourself. In light of the evidence, is it possible that the Flat Earth Society is correct? Present at least 3 pieces of evidence that support the Earth being round. Also discuss the importance of Aristotle's lunar eclipse observations made 2,400 years ago (see Chapter 3).

Photographic evidence proves that the earth is round. If you view earth from a distance, it clearly shows a sphere. I can't think of a single reason as to why we'd fabricate a story about the earth being round. There wouldn't be a purpose in doing so. However, if the photographs aren't enough proof, you can simply view a lunar eclipse. The shadow created by the ecplipse will show a round edge and this can only be produced by a sphere. Another type of evidence is the fact that time zones exist. We wouldn't have time zones if the earth was flat. Finally, a more obvious approach to proving the earth isn't flat is the fact that people and objects aren't falling off the edge. If the earth was flat, people and objects would be disappearing. I'd say with the photographic evidence combined with general knowledge, we can absolutely say that it's impossible for the Flat Earth Society to be correct. Aristotle's lunar eclipse observations were the beginning of the geocentric model and allowed for an in depth theory of planetary motion. There's no telling what the lack of observation would have made on the Greek model. This was also very clear proof that the earth is round as it produced a sphere shaped shadow. We're obviously taught at a young age that the earth is indeed round and not flat. However, I haven't though about it much until now. I think I'll take a moment and observe the next lunar ecplipse to gain a further appreciation of the work that's gone into researching this. I'm actually able to explain and prove the earth is round other than showing photos. I'm not someone to believe the photos are fake. However, I also haven't observed the earth from a distance with my own eyes. The information in this lesson proves that you don't need pictures to demontrate the earth is sphere shaped.

4. The climate histories of Venus and Mars make it clear that it's not easy to get a pleasant climate like that of Earth. How does this affect your opinion about whether Earth-like planets might exist around other stars?

Technically both Venus and Mars are Earth like planets, small rocky and with atmospheres on which water in some form or another exists. Venus has a number of issues that prevent it from being more Earth like, how this happened, we cannot be sure, but the period of rotation of Venus on it axis is a major issue, it spins at about the same rate that it orbits the Sun around 270 days, this slow rotation means that heat does leave the planet quickly, the day side heats up and this causes the night side not to cool enough, add this to being 30 million miles on average nearer to the Sun and any liquid we have on Earth is gas on Venus, this means that the atmosphere is thicker and the pressure of that 'air' on the surface is much greater, crushly so. The absence of a moon also adds to the problems as it means the tides are not balanced as they are on Earth. Mars is to small to hold a significant atmosphere. That said the fact that we have three planets that are small and rocky within a distance of our Sun means that the probabilities of other planetary systems being similar appear much greater. The fact that currently we can only detect planets that are very unsuitable is not a negative thing, we are only just finding these planets and systems, the first was not officially confirmed until 1995, and each star that has been checked seems to have at least one planet that is Jupiter sized or bigger. They do seem very unlikely canidates to have Earth like planets, most of those discovered are orbiting their planets in days rather than years are huge bloated gas giants that would have atmosheres at thousands of degrees, but they are there. We now have technology such as the Kepler space telescope that is designed to look at hundreds of starts at once, and is finding more 'candidates' on a daily basis, each of these candidates has to be observed for more than one year, and the candidate planet will need to be detected more than once, now a planet that orbits its parent star once a year may be much more Earth like, and so once we have sufficient data then we will go from probabilty of such planets existing to the knowledge that they do, as each planet is identified the probablility of there being more increases exponentially, then we need to check the spectroscopy of the planet, separating it from that of the parent star, this is time consuming but not difficult, measures of the atmosphere will give indications of life, we cause specific effects on our atmosphere that give away our presence and out industrialisation, detect these indicators and we can reasonably sure that someone else is out there This is all very new science, it is changing all the time,

3. What kinds of tests are used to validate astrology and what are the results? Why do you believe astrology remains so popular around the world even though it has failed all scientific tests of its validity? Do you think the popularity of astrology has any positive or negative social consequence?

Test by Barth & Bennett. James Barth and James Bennett, Economists at George Washington University, examined the horoscopes of tens of thousands of men who had reenlisted in the Marine Corps. They were looking for a trend among soldiers that favored astrological signs ruled by Mars, the god of war. However, they found instead an equal number of men who were born under the influence of Venus, the so-called planet of love. Test by Silverman. Psychologist Bernie Silverman of Michigan State University tested the effect of astrological compatibility on marriages. He surveyed astrologers across the country on the compatibility of the twelve Zodiac signs. In studying, 2,978 marriage and 478 divorce records in Michigan, Dr. Silverman found couples whose marriages were made in horoscope heaven united and split up just as frequently as those who were not astrologically compatible. The negative impact is the amount of money that's wasted on Astrology. This could be put toward something better. Also, we're allowing something that has been proven false to dictate our lives in a way.

3. Briefly discuss how the Sun affects people on Earth. Be sure to consider not only factors such as its light and warmth, but also how the study of the Sun has led to new understandings in science and to technological developments. Describe at least 1 invention that uses Sunlight and has helped or will help improve the quality of human lives.

The Sun has both negative and positive impacts. It keeps the human race warm and doesn't allow it to get to cold. It's a major part in keeping a balanced climate. It also reacts with the human body to create vitamin D. It's also dangerous in that its rays can cause skin cancer and damage to eyes. The most obvious invention that comes to mind is solar power. We've discovered how to harness the power of the Sun and use that energy. This has already improved human lives in that it's clean energy and I don't believe we've found the limits of that energy.

4. Einstein's discovery that energy and mass are equivalent has led to technological developments that are both beneficial and dangerous. Discuss several such developments. Describe at least one beneficial development and one dangerous development. Overall, do you think the human race would be better or worse off if it had never been discovered that mass is a form of energy?

The discovery of this relationship lead to the development of the atomic bomb. I am not sure if the benefit is greater than the shortcomings, but it is also true that the bomb was only used twice in a war, and the last time was about 65 years ago (Negative). This relationship created the possibility for nuclear power reactors (Positive). I do hope (and think) that the benefits will eventually really outweigh the disadvantages, in everyone's view.

5. Imagine you had a good fortune to find a rocky meteorite in your backyard. Qualitatively, how would you expect its ration of potassium-40 and argon-40 to be different from other rocks in your yard?

The meteorite will have a smaller ratio of potassium-40 to argon-40 than the other rocks.

4. Many common phrases reflect the ancient Earth-centered view of the universe. For example, the phrase "the Sun rises each day" implies that the Sun is really moving over Earth. You know that the Sun only appears to rise as the rotation of the earth carries you to a place where you can see the Sun in the sky. Identify other common phrases that imply an Earth centered viewpoint.

The same could also be said regarding "the sun is setting". The Earth is actually moving at this point and the Sun is stationary. We also might refer to the "stars in the sky" when they're actually quite far from Earth. These are just a few examples of Earth-Centered views.

4. It took thousands of years for humans to deduce that Earth is spherical. For each of the following alternative models of Earth's shape, identify one or more observations that you could make for yourself that would invalidate the model. A. A flat Earth B. A cylindrical earth (shaped like a fallen log), like that proposed by Anaximander C. A football shaped Earth

There is one observation that invalidates all three - a lunar eclipse. A lunar eclipse is the shadow of the Earth cast on the moon, and it is always a circle. If the Earth were any other shape, the shape of the Earth's shadow would also change. The Greeks knew that the Earth was round centuries before Columbus, and they knew this by observing lunar eclipses.

1. One of the most pressing environmental issues on Earth is the extent to which human emissions of greenhouse gases are warming the planet. Some people claim that part or all of the observed warming over the past century may be due to changes in the Sun rather than to anything humans have done. Discuss how a better understanding of the Sun might help people comprehend the threat posed by greenhouse gas emissions. Why is it so difficult to develop a clear understanding of how the Sun affects the earth's climate?

There's no doubt we're experiencing global warming. I believe a better understanding of the Sun might help people understand what we're doing to the climate. It's easy to point the fingers elsewhere when discussing the causes of global warming. It's obvious that the presence of human life and our daily activities are generating heat. If you have a basic understanding of the Earth's atmosphere, you know that heat doesn't just disappear. The sun is similar in that the earth absorbs the Sun's energy and inferred radiation is sent back into space. However, greenhouse gasses trap some of this radiation. It's important for people to understand that additional greenhouse gasses cause additional heat from the Sun's energy to be trapped. Together, this combination increases the temperature even more. It's very difficult to understand how the Sun affects the Earth because we're not sure what it would be like if our greenhouse gasses didn't exist. Research can only demonstrate how a combination of factors is impacting our climate. We're in a very different place than where we were even 20 years ago. I believe we're becoming more aware of the importance of the environment and the role we play in it. However, I believe we have plenty of room for improvement.

3. Although many people may have gleaned hints of the vast size of the cosmos, Dutch astronomer Christian Huygens may have been the first person to truly understand both the large sizes of other planets and the great distances to other stars. This is what he wrote, way back in about 1690: "How vast those Orbs must be, and how inconsiderable this Earth, the Theater upon which all our mighty Designs, all our Navigations, and all our Wars are transacted, is when compared to them. A very fit consideration, and matter of Reflection, for those Kings and Princes who sacrifice the Lives of so many People, only to flatter their Ambition in being Masters of some pitiful corner of this small spot." What do you think he meant by this statement?

This can be translated in endless ways. In my opinion Huygens was referring to how small we really are without realizing it. Most people see earth as this huge and busy place. However, earth is very small in scale when taking the universe into consideration. When he references being masters of earth, I think he's referring to these individuals as fools for thinking they're as powerful as they believe they are. The thought of being powerful on earth is quickly shattered by what's surrounding earth. There's been times where I've though about how small the earth was. However, reading this quote has really brought on a new perspective. When comparing ourselves on certain levels we may amount to something large. However, when comparing ourselves to what's beyond earth, we're much smaller than we can ever imagine. In terms of applying this to life, I believe it's important to keep in mind what a small piece of the puzzle we are.

4. People can study terrestrial planets up close by landing on them, but Jovian planets have no surfaces to land on. Suppose that you are in charge of planning a long-term mission to "float" in the atmosphere of a Jovian planet. Describe the technology you would use and how you would ensure survival for any people assigned to this mission.

Well we already had one when a probe initially attached to the Galileo orbiter descended into Jupiter's atmosphere. It didn't last long though. For something long term some kind of balloon would be required. Since most of Jupiter's atmosphere is hydrogen and helium, the only thing that would work as a buoyancy agent would be hot hydrogen (like hot air in a Earth-based balloon). At least there would be less danger of explosion since there is no free oxygen in Jupiter's atmosphere.

1. Suppose you discover a planet in another solar system that has a circular orbit and an axis tilt of 35 degrees. Would you expect this planet to have seasons? If so, would you expect them to be more extreme than the seasons on Earth? How does latitude relate to your answer? Also explain how the poles would be affected.

Yes, it would definitely have seasons, and they would be more extreme than those which Earth has because of the stronger tilt. The seasons would be more severe because in summer the pole would be be even more exposed to the Sun than on Earth, and in winter is would have even less exposure, therefore a longer summers and winters than on Earth and shorter spring and fall seasons. In fact, we have an even more extreme example: The axes of Uranus is at approximately 90 degrees, and if it weren't a gas giant, it would have the most severe seasons possible - maybe it does anyway, considering that it's the 7th planet in our Solar system!

1. Suppose that the material that formed Jupiter came together without any rotation so that no "Jovian nebula" formed and the planet today wasn't spinning. How else would the Jovian system be different? There are many effects to be considered.

• There wouldn't be any belts or zones in the atmosphere. • There wouldn't be any magnetic fields. • Jupiter would be a perfect sphere.