THE SOLAR SYSTEM : all homework questions
(Ch 3 Visual Skills Check) An asteroid with an average orbital distance of 2 AU will orbit the Sun at an average speed that is:
A little slower than the orbital speed of Mars.
(Ch 8 Visual Skills Check) Compare the two graphs, which show the decay of potassium-40 and uranium-235. Which element is more radioactive (undergoes radioactive decay more quickly)?
Uranium-235. This is because the graph of uranium-235 is much steeper than the graph for potassium-40 (figure 8.15). This means it undergoes radioactive decay much more quickly, resulting in 6 half-lives by the time it has formed 5 billion years ago, whereas potassium-40 only results in 3 half-lives by the time it was formed 5 billion years ago
Why does Neptune appear blue? Possible answers are (a) Neptune is hotter, which gives bluer thermal emission; (b) Methane in Neptune's atmosphere absorbs red light; or (c) Neptune's air molecules scatter blue light (so-called Rayleigh scattering). Furthermore, do any of these mechanisms (heat, methane, scattering) account for the sky blue of the Earth's atmosphere?
B; Neptune appears blue because the methane in its atmosphere absorbs red light; the atmosphere absorbs the red light and allows the blue light to scatter and therefore show through. This process is known as selective absorption. Rayleigh scattering is responsible for the sky blue of the Earth's atmosphere. In the Earth's case, the blue wavelengths of sunlight are scattered easily by the molecules in the atmosphere compared to wavelengths like red and green that are longer, which leads to the blue sky
(Ch 2 Visual Skills Check) Which of the four labeled points represents the beginning of spring for the Southern Hemisphere?
C
Finally, let's imagine a "what if." Consider the statement below from Plato. What if our Earth was cloudy all the time. I don't mean that in a terrible sense, as on Venus, but just opaque so that no one, historically, ever observed the heavens. How do you think astronomy would have evolved? And how might the course of human advancement have been altered?
(no wrong answer just use imagination)
How long would the year be for the Earth if the Sun had twice its present mass (assume the Earth's orbit doesn't change). If the Sun had twice its present mass and twice its present diameter, does your answer change? Why or why not? For this problem you need the version of Kepler's 3rd as derived by Newton, shown in class (see slides) or in the textbook.
0.71 earth years = new orbital period with the Sun's mass doubled. If the sun's diameter was doubled in addition to the mass, it would not change the orbital period anymore because the mass is still doubled from part one of the question (the diameter does not have an effect on orbital period).
(Ch 8 Visual Skills Check) What fraction of the original uranium-235 should be left after 3.5 billion years?
1/32. This is because 1 half-life is 50% (½), so after 3.5 billion years, it would be ½^5, making 1/32 of it left. This fraction represents the amount of uranium-235 that has decayed over time.
(Ch 3 Visual Skills Check) How far does the planet in the questions above orbit from the Sun?
10 AU
Finally, a new comet has been discovered, named after its 2 discovers, Swift-Taylor. Astronomers have discovered that this comet was last seen 1000 years ago from olde England. Assuming that this time lapse is a good measure of its orbital period, what would be a decent estimate of its orbital semi-major axis? If Swift-Taylor's orbit had to cross the orbit of the Earth to be seen with the naked eye, what minimum value of the orbital eccentricity is required?
100 AU would be Swift-Taylor's estimated orbital semi-major axis. The minimum value of the orbital eccentricity required would be .9898 AU = e
(Ch 3 Visual Skills Check) Suppose graph a showed a planet on the red line directly above a value of 1000 AU^3 along the horizontal axis. On the vertical axis, this planet would be at:
1000 years^2
(Ch 3 Visual Skills Check) Uranus orbits about 19 AU from the Sun, based on a graph, its approximate orbital speed is between about:
5-10 km/s.
How big an object causes a "shooting star"? Pick the best answer and explain: (a) a grain of sand or a small pebble; (b) a boulder; or (c) an object the size of a small house
A, a grain of sand or a small pebble. This is because despite the smaller size, the object experiences travel speeds at such high rates through the atmosphere that they heat up and produce the light of a shooting star.
Which of the following was not a major advantage of Copernicus' Sun-centered model over thePtolemaic model? Explain. (a) It made significantly better predictions of planetary positions in our sky. (b) It offered a more natural explanation for the apparent retrograde motion of planets in our sky. (c) It allowed calculation of the orbital periods and distances of the planets
A; Copernicus' Sun-centered model did not make significantly better predictions of the planetary positions in our sky compared to the Ptolemaic model, but it was more accurate in other senses. He still believed that the planet's orbits must be circular rather than more ellipse-like.
(Ch 9 Visual Skills Check) A tectonic ridge appears to connect points 3a and 3b, crossing several craters. From its appearance, we can conclude that it must have formed:
After the area was cratered. This is because the tectonic ridge is still observable and appears to go over the area at a much higher dimension than the craters and flat surfaces. If it was formed before the area was cratered, then the craters (depending on how deep the crater was), would have demolished or severely diminished the tectonic ridge.
How many of the five terrestrial worlds (Moon included) have lava plains or shallow-sloped (shield)volcanoes? One? Two? Three? Four? All Five? Give examples.
All five of the terrestrial worlds have either lava plains or shield volcanoes. An example for the Earth is Hawaii, as it is a result of shield volcanoes and other certain regions in southern Asia are remnants of lava plains. Mars has the largest shield volcano in the solar system, Olympus Mons and we know it has areas covered by lava plains based on research and landers sent there. Venus is known for having results of volcanic activity, as the entire surface has been shaped by it, leaving behind lava plains and shield volcanoes. The Moon has lava plains known as Maria from old volcanic eruptions, but it does not have shield volcanoes like the other terrestrial planets. The surface of Mercury is thought to be the result of historical volcanic activity and has formations that resemble shield volcanoes
What is the difference between the Solar System, the Milky Way, and the Universe?
Although these terms are often used interchangeably, the Solar System, the Milky Way, and the Universe all actually refer to different aspects of space. The Universe, as a whole, is the entirety of everything in existence, including our galaxy, the Milky Way, which lies within it. The Universe consists of (in order of largest to smallest) local superclusters, local groups within those superclusters, our Milky Way Galaxy, our Solar System, and all the planets, including Earth itself. Earth resides within our Solar System, which is where the sun and all other planets, moons, and smaller objects reside as well. Our Solar System resides within the Milky Way Galaxy, which is assigned to a local group, or, a group of more than 80 galaxies. In all, the remaining billions of galaxies that subsist belong to the Universe as a whole, which again refers to the totality of everything in existence
(Ch 2 Visual Skills Check) Which of the four labeled points represents the day with the most hours of daylight for the Northern Hemisphere?
B
Explain which one of the following choices is correct. Compared to their values on Earth, on another planet (such as Mars) your (a) mass and weight would both be the same; (b) mass would be the same but your weight would be different; (c) weight would be the same but your mass would be different.
B is the correct answer because of the difference in gravitational field strength between Earth and Mars. Mars has weaker gravity therefore mass would be the same but your weight would be different
Which of the following lists the major steps in solar system formation in the correct order: (a) collapse, accretion, condensation; (b) collapse, condensation, accretion; or (c) accretion, condensation collapse? What do these 3 terms refer to anyway?
B lists the major steps in the solar system formation in the correct order. This is because collapse is the first step and it refers to the gravitational collapse of a region within a giant molecular cloud. Next, condensation refers to the temperature and density increase in the central region of the molecular cloud. Finally, accretion is the third step and refers to the particles sticking together and colliding, forming larger particles and growing into planetesimals
What is the longest lasting internal heat source responsible for geological activity? (a) accretion (gravitational heat of formation); (b) decay of long-lived radioactive elements such as uranium; or (c) sunlight? Explain
B, the decay of long-lived radioactive elements such as uranium is the longest lasting internal heat source responsible for geological activity. This is because atomic particles increase the temperature of the planetary interior; many different isotopes are already present in the interior of Earth
If Earth were twice as far from the Sun, the force of gravity attracting Earth to the Sun would be (a) twice as strong; (b) half as strong; (c) one quarter as strong; (d) just the same.
C is correct because the force of gravity is proportional to the inverse square of the distance between the two objects. F=1/r^2, so then if r is 2, it becomes 1/(4r^2). This means that the force of gravity would be ¼ as strong, or, C
Explain which one of the following choices is correct. A car is accelerating when it is (a) traveling on a straight flat highway at 70 miles per hour; (b) traveling on a straight uphill road at 40 miles an hour; (c) traveling on a circular race track at a steady 120 miles per hour.
C is the correct answer. This is because when a car is moving in a circle it is constantly changing its direction, which also means there is a change in velocity, resulting in acceleration
What's unusual about our Moon? Is it that (a) it's the only moon of a terrestrial planet? (b) it's by far the largest moon in the Solar System; or (c) it's surprisingly large compared with the planet it orbits? Explain your response to all three possibilities
C, it is surprisingly large compared with the planet it orbits. It is not the only moon of a terrestrial planet, because Mars has two smaller ones. It is not the largest moon in the solar system, because that is Jupiter's moon Ganymede. However, the earth is about one fourth the width of Earth, making it much bigger in scale than other planet's moons (such as Jupiter and Mars),
Which of these groups of particles has the greatest mass? (a) a helium nucleus with two protons and two neutrons; (b) four electrons; (c) four individual protons.
C, or, four individual protons, have the greatest mass because if you add up the mass of the four protons and compare it to the mass of a helium nucleus, the helium is slightly less massive.
Can an asteroid be made of pure metal? Pick the best answer and explain: (a) No, all asteroids contain rock; (b) Yes, it must have formed where only metal could condense in the solar nebula; (c) Yes, it must be from the core of a shattered asteroid
C, yes, it must be from the core of a shattered asteroid. This is because even though asteroids are made of mostly metal and rock, the material condenses at relatively cool temperatures in certain regions of the solar nebula. Therefore, a few asteroids appear to be made mostly of metal, such as iron, because they may be fragments of the metal cores of shattered worlds.
About what fraction of the Earth's atmosphere is CO2? a) 90%, b) 1%, or c) less than 0.1%? And how do we know?
C; 0.04% of the Earth's atmosphere is carbon dioxide, so less than 0.1%. We know this because scientists have sampled the air at several sites around the world.
Galileo's contribution to astronomy included: (a) discovering the laws of planetary motion. (b) discovering the law of gravity. (c) making observations and conducting experiments that dispelled scientific objections to the Sun-centered model Explain.
C; Galileo did not discover the laws of planetary motion, Kepler did, and he did not discover the law of gravity, Newton did. He did however make observations that resulted in his Sun-centered model, greatly impacting the future of studying astronomy.
Which moon shows evidence of rainfall and erosion by a liquid: (a) Europa; (b) Ganymede; (c) Titan; or (d) Callisto? What is the evidence?
C; Saturn's moon Titan shows evidence of rainfall and erosion by liquid. The evidence comes from part of the Cassini mission where images and data collected revealed river-like channels, lake beds, and shorelines on Titan's surface. These features suggest the presence of liquid compounds like methane or ethane, which forms rivers and lakes, and causes erosion similar to Earth's water erosion
Tycho Brahe's contribution to astronomy included: (a) inventing the telescope. (b) proving the Earth orbits the Sun. (c) collecting data that enabled Kepler to discover the laws of planetary motion. Explain.
C; Tycho Brahe did not invent the telescope, Galilei did, and he also did not prove the Earth orbits the Sun, Copernicus did. He did however collect important data that allowed Kepler to discover his laws of planetary motion.
Which of the following is a strong greenhouse gas: (a) nitrogen, (b) argon, (c) water vapor, or (d) oxygen? If we planted a whole lot more trees (which China is doing for other reasons) and increased the molecular oxygen content of the Earth's atmosphere, would this cause our planet to warm up? Explain your answers
C; Water vapor is a strong greenhouse gas because it traps the Sun's heat. If one were to plant a lot of trees, increasing the molecular oxygen content of the Earth's atmosphere, this would not cause our planet to warm up because molecular oxygen is not a greenhouse gas and does not have heat-trapping properties.
Some gas or ice giant planets give off measurably more energy than they receive (absorb) from the Sun because of which of the following: (a) nuclear fusion in their cores; (b) tidal heating; or (c) ongoing contraction or differentiation (meaning, settling of heavier elements toward the center)? Which of the four giant planets in our Solar System is "not like the others" in this regard?
C; some gas or ice giant planets give off measurable more energy than they receive from the Sun because of ongoing contraction or differentiation. As the planets slowly contract and their heavier materials sink toward the center, they emit energy in the form of heat, which is a part of their overall energy output. Of the four giant planets, Uranus is not like the others in this regard. This is might be because of the lack of significant gravitational interactions or tidal forces within Uranus, unlike other gas giants. Its internal structure and composition might also contribute to its relatively lower heat production compared to the other gas giants
Where is most of the CO2 that has outgassed from the Earth's volcanoes: (a) in the atmosphere, (b) in space, (c) dissolved in the ocean, or (d) in rocks? Explain. What about Venus, where is its outgassed CO2? Does Venus even have volcanoes?
C; the oceans on Earth are a massive carbon sink that Venus simply does not have. CO2 on the Earth and Venus both come from outgassing of volcanoes, but for Venus that CO2 stays in the atmosphere as a powerful, warming greenhouse gas; on earth, much of that CO2 is instead dissolved in the ocean
(Ch 9 Visual Skills Check) Label 1a lies on the rim of a large crater, and label 1b lies on the rim of a smaller one. Which crater must have formed first?
Crater 1a must have formed first. This is because the only way crater 1b could still be that deep and prevalent is if it forms after crater 1a, which has eroded a lot since the time it was formed based on its flatter and smoother surface
(Ch 2 Visual Skills Check) Which of the four labeled points represents the day with the most hours of daylight for the Southern Hemisphere?
D
A new NASA mission has gone into orbit around Venus (I am making this up), and it has discovered an actively erupting volcano. Would you consider this reasonable, or a surprising discovery? And why?
Discovering an actively erupting volcano on Venus would be a surprising and groundbreaking discovery. Venus is thought to have a vastly different tectonic activity compared to Earth, with debates about its surface being either nearly inactive or having highly episodic activity. While sulfur dioxide (SO2) in Venus's atmosphere indicates some ongoing volcanic processes, it was not enough evidence to confirm recent volcanic activity until this hypothetical discovery. Identifying active volcanism on Venus would challenge previous assumptions and significantly reshape our understanding of the planet's geological processes.
Why was it so important for the Soviet Union to launch the first artificial Earth satellite and the first human into space (Yuri Gagarin)?
Even though we were at peace with the Soviet Union, when they launched the first artificial Earth satellite and human into space, it sent us into an adversarial competition. They had newspapers and advertisements exclaiming how they were now "ahead" and "better" than America, mockingly saying that the U.S. needs to "keep up." These events were huge, culturally, making it a fantastic propaganda coup and demonstrating the superiority of the Soviet Union.
State Newton's three laws of motion. For each law, give an example of its application
First law (inertia): an object will not change its motion unless a force acts on it; example : a ball rolling down a hill will not stop unless friction stops it Second law (force): the force of an object is equal to its mass times its acceleration; example : an aircraft's motion resulting from aerodynamic forces, aircraft weight, and thrust Third law (action and reaction): when two objects interact, they apply forces to each other of equal magnitude and opposite direction; example : in a bird's flight motion the wings of the bird push air downwards as action force, and the air pushes the bird upwards as reaction force
We use radio waves, which travel at the speed of light, to communicate with astronauts and robotic spacecraft. How long does it take a message to travel from Earth to a) an astronaut on the surface of the Moon?; or from Earth to a spacecraft at b) Mars at its closest to Earth (about56 million km)?, c) Mars at its farthest from Earth (about 400 million km)?, and d) the NewHorizons spacecraft, now well beyond Pluto at a distance from Earth of 56.4 AU (as of today,Sept. 6)? e) If you sent a radio message to New Horizons today, how long would it take in total to hear back from the spacecraft at minimum?
How long does it take a message to travel from earth to : (a) Astronaut on moon : 1.28 s (b) Spacecraft on mars (closest point) : 186.67 s (c) Spacecraft on mars (farthest point) : 1,333.33 s (d) New Horizons spacecraft : 28,124.4 s (e) New Horizons and back to earth : 56,248.8 s (multiplied "d" by two because it goes there and back again)
How can icy moons, especially smaller icy moons, have active geology when compared with relatively inactive rocky bodies of the same size (give two reasons)?
Icy moons can have active geology, even when compared with relatively inactive rocky bodies of the same size, because ice melts at lower temperatures, meaning tidal heating can melt the internal ice and drive new activity (while rock melts at higher temperatures and the Jovian planets have very cool temperatures). Also, tidal forces can have an effect, as the gravitational pull from the massive Jovian planets (where the icy moons often are) can cause flexing of the moon's interior due to gravitational interactions, which gente heat through tidal friction. This continuous flexing and heating can lead to geological activities like liquid water beneath the icy crust, resulting in tectonic activities.
The Earth's orbit has an eccentricity of 0.02 (2%). If the Earth's orbit were a perfect circle, would we have or not have seasons? Explain your answer.
If Earth's orbit were a perfect circle with no eccentricity, the seasons would still occur. The tilt of Earth's axis is the primary factor responsible for the seasons, not the shape of its orbit. As Earth orbits the Sun, its axis remains tilted at approximately 23.5 degrees relative to its orbital plane. This tilt causes different parts of the Earth to receive varying amounts of sunlight throughout the year, resulting in the seasons. Even with a circular orbit, this tilt would still cause the Northern and Southern Hemispheres to experience seasons as they alternately receive more direct sunlight (summer) or less direct sunlight (winter) during their respective orbits around the Sun. Therefore, the absence of orbital eccentricity wouldn't eliminate the seasonal changes caused by Earth's axial tilt.
It is estimated that that there are a million asteroids 1 km in diameter or larger. If a million asteroids one kilometer across were all combined into one object, how big would it be? Would it be as big as a terrestrial planet, or even the Moon? You can assume the asteroids are spherical, and the volume of a sphere of radius R is 4/3 π R^3
If a million asteroids 1 km in diameter were combined into one object ,the volume would be around 523,600 km. this would be nowhere near the volume of the Moon or another terrestrial planet. (steps for solving below) : (a) Diameter = 1 km which means radius = 0.5 km (b) Insert radius into volume formula : V = (4/3)pi x R^3 - R = 0.5 - V = (4/3)pi x 0.5^3 - Solve for V and then multiply the volume of a single asteroid by 1 million (because they are being put together as one) = 523,600 km
As you know, Saturn's spin axis has a tilt similar to that on the Earth, so what season is it likely to be on Saturn in 2025? Hint: you have a choice of two
In 2025, Saturn is likely to be making the transition into autumn, and the autumnal equinox is predicted to occur in the northern hemisphere about halfway through 2025. A way we are able to estimate seasons on Saturn is through the rings, specifically the spokes on the rings; we only see the spokes in years preceding and following equinoxes
How would you compare the impact crater "density" (number of craters per square kilometer) between Io and our Moon? What accounts for this difference?
Io, due to its intense volcanic activity, has a significantly lower impact crater density compared to our Moon. The constant volcanic eruptions on Io continuously reshape its surface, erasing or covering existing impact craters. This ongoing geological activity conceals the evidence of older impacts, resulting in fewer visible craters (we have never seen an impact crater on Io meaning it is extremely young as well). Conversely, the Moon lacks such dynamic processes, allowing impact craters to accumulate and persist over billions of years, leading to a higher crater density on its surface. This disparity is primarily due to Io's active volcanism masking or eliminating older craters, while the Moon's inactive surface preserves impact craters over time
Neptune was first spotted (knowingly) by German astronomer Johann Galle in 1846, but he is not credited with its discovery. Why is that?
Johann Galle observed Neptune in 1846 based on Urbain Le Verrier's predictions, but Le Verrier and John Couch Adams independently calculated its existence. Le Verrier published his predictions first, and although Galle confirmed Neptune based on his calculations, both Le Verrier and Adams are credited with its discovery due to their separate but concurrent mathematical predictions.
What is the Great Red Spot (GRS)? Is it related to any terrestrial weather phenomenon?
The Great Red Spot is a giant continuous storm more than twice as wide as all of earth. This spot is somewhat like a hurricane, except that its winds circulate around a high pressure region rather than low pressure. This spot is also very long lived, and it is an anticyclone that has high pressure creating a persistent storm.
Jupiter and Saturn are said to have "fuzzy cores." What does this mean? Does the Earth have a fuzzy core?
Jupiter and Saturn are described as having fuzzy cores due to the challenge in defining a clear boundary between their cores and the surrounding layers within these gas giants. This absence of a well-defined boundary results in the term "fuzzy." In contrast, Earth does not possess a fuzzy core because the core's distinct layers are more clearly defined, allowing us to differentiate and identify the composition of each layer. Earth's core comprises a solid inner core and a liquid outer core, and the ability to discern these layers and their composition distinguishes it from having a fuzzy core
Jupiter and Saturn are considered to be close siblings. Why? Give two important ways in which they are different as well.
Jupiter and Saturn are regarded as close siblings due to their shared characteristics. Both are gas giants dominated by helium and hydrogen and both possess comparable rocky cores. Additionally, they each have a ring system, although Saturn's rings are notably more prominent. Despite these similarities, crucial differences exist between them as well. Jupiter notably surpasses Saturn in size, standing significantly larger. Moreover, their atmospheric attributes diverge significantly: Jupiter showcases vibrant storms and bands, while Saturn exhibits subtler, more subdued patterns and colors across its atmosphere (as discussed above)
Why does Jupiter produce so much internal heat? That is, what is the ultimate source of this energy? How do we know this heat is being released?
Jupiter produces so much internal heat because its interior is heated through its own weight, and it is the largest planet. It does this by squeezing the interior when external forces, such as gravity, are balanced by a pressure-gradient force, and its surface is heated mostly by the Sun. Moreover, the residual heat left over from the original collapse of the primordial nebula to form the entire Solar System has contributed to its heat also. The ultimate source of its energy is likely due to the helium rain because it doesn't dissolve in metallic hydrogen. This rain falls from the top of Jupiter's highly compressed metallic hydrogen layer towards the center of the planet, which then generates kinetic energy. We know this heat is being released because of infrared observations that have revealed its upper layer is very warm (it emits thermal radiation).
Why are the colors in Jupiter's atmosphere and in its clouds different from those on Saturn? Why does Saturn sometimes show butterscotch colors and sometimes show bluish colors?
Jupiter's and Saturn's atmospheric colors arise from a blend of factors including composition, temperature, and the existence of specific chemical compounds. Jupiter's atmosphere, containing methane, ammonia, and water vapor, creates interactions between these, generating the planet's characteristic swirls and bands. The red and brown hues on Jupiter are likely a result of phosphorus and sulfur. In contrast, Saturn's varying colors stem from its unique composition. Saturn's alternating shades, from butterscotch to bluish, occur due to the interaction of light with its atmosphere, which could also be influenced by seasonal shifts, diverse viewing angles, or changes in atmospheric conditions
Why is Jupiter so much more dense than Saturn? Could a planet be smaller in size than Jupiter but greater in mass?
Jupiter's higher density in comparison to Saturn is because of their compositional differences. Jupiter mainly consists of heavier gases like hydrogen and helium, accounting for its greater density. Although Saturn shares a similar gas composition, Jupiter's distinct distribution and proportions of these gases contribute to its higher density. It's feasible for a planet to be smaller in size than Jupiter but possess greater mass due to the independent nature of density, size, and mass. If a smaller planet (Saturn in this case) comprises denser materials, it could outweigh a larger planet made of lighter substances. Hence, the composition of a planet stands as a crucial determinant in these distinctions.
Why does Jupiter have such a strong magnetic field, the strongest of all the planets? Clue: How is this magnetic field generated?
Jupiter's magnetic field is likely generated by a swirling mass of hydrogen deep within the planet. When this hydrogen is crushed due to the incredible pressure near Jupiter's core, this material becomes a metallic liquid that can conduct electricity and generate a magnetic field when stirred
(Ch 9 Visual Skills Check) The region around 2b has far fewer craters than the region around 2c. The crater floor at 2a is also flat and smooth, without many smaller craters on it. Why are regions 2a and 2b so smooth?
Lava flows covered craters that once existed in these regions. This is because billions of years ago, much of the moon's surface was hardened with covered luna lava, making those craters disappear or go faint.
Why isn't liquid water stable on Mars today (except deep in impact basins), and why do we nonetheless think it flowed on Mars in the distant past?
Liquid water is not stable on Mars today because of the low and thin atmospheric pressure that would cause it to boil and evaporate almost immediately. Because of this thin atmosphere, water can't exist in its liquid state on the surface so instead, it either freezes or vaporizes quickly. These cold temperatures also would cause it to freeze, thus making it challenging for liquid water to exist. We think liquid water flowed on Mars at one point because of the valleys and channels that suggest the presence of flowing water in the past. Rovers have also discovered minerals that typically form in the presence of water, and it is believed that Mars had a thicker atmosphere in the past, which could have supported higher temperatures and allowed for liquid water to exist. Further, some meteorites that came from Mars and landed on Earth contain traces of minerals that require water to form
Mars' orbital eccentricity is 9%, much larger than the Earth. If the tilt of its spin axis were totally perpendicular to its orbit, would it have seasons? Why or why not? (And guess what,Mars' axial tilt is actually similar to that of the Earth and it has a large orbital eccentricity, so its seasons are pretty wild!).
Mars would not have seasons if the tilt of its spin axis was totally perpendicular to its orbit. This is because every area on Mars would be facing the Sun at the same exact distance and tilt at every single complete rotation that Mars made. This makes every area on Mars a specific distance and feel the same amount of heat from the Sun every rotation
NASA is about launch a big mission to Jupiter (next year in fact). What is this mission, and what is its primary goal or mantra?
NASA is about to launch Juno, where it will allow us to examine Jupiter from its innermost core to the outer reaches of its magnetic force field. During the mission, Juno will map out Jupiter's gravity and magnetic fields to learn more about what its interior structure is like. The goal is to peer beneath the clouds around Jupiter for the first time so that we can learn more about its atmosphere
Why does nuclear fusion require such high temperatures and pressures?
Nuclear fusion demands high temperatures and pressures because atomic nuclei, being positively charged, repel each other due to electromagnetic forces. To initiate fusion, nuclei must be brought close enough for the strong nuclear force to overcome this repulsion and bind them together. High temperatures provide the necessary kinetic energy for particles to overcome this repulsion, while high pressures confine and compress the fuel, enabling the conditions required for fusion to occur.
Choose four features on the global map of Mars (Figure 9.25 in the text) and explain the nature and likely origin of each.
Olympus Mons : The largest volcano in our solar system, Olympus Mons is a substantial shield volcano on Mars, towering three times taller than Mount Everest. Its expansive slopes suggest its creation from volcanic activity, likely due to the low viscosity of Martian volcanic materials and the absence of plate tectonics Tharsis Bulge : A massive volcanic plateau on Mars, Tharsis Bulge hosts prominent volcanoes like Olympus Mons and Pavonis Mons. Its formation is likely linked to intense volcanic activity and geological processes, emerging from magma originating in the mantle and developing over a stationary hotspot within the crust. Hellas Basin : A vast impact crater on Mars characterized by a flat floor covered with plains and dunes. Its formation is attributed to a colossal celestial body's impact, creating shockwaves that deformed the terrain around the basin. Volcanic activity and erosion have also played roles in modifying its features. Some evidence suggests the possibility of past liquid water, as channels and valleys leading into the basin hint at this potential. Valles Marineris : A network of interconnected canyons on Mars indicating extensive geological activity and erosion. Its formation is thought to have resulted from volcanic processes weakening the crust, leading to collapse and the creation of the canyon system. Erosion, weathering, and possible water flows or floods over time have contributed to carving the canyon walls
Now, imagine that we found a new ice giant orbiting 100 times as far away from the Sun as the Earth does, and that the orbit is circular. How long does this planet take to go around the Sun?
P = 1,000 earth years
If we moved the Earth 5.2 times as a far away from the Sun as it is now (but kept its nearly circular orbit), use Kepler's 3rd law to figure out how long the year would be. (Remember, for Kepler it was all a question of ratios; he didn't know about big G.) Do any planets today orbit at that distance? Is your answer correct? Hint: in units of Earth years and AUs, Kepler's Third Law can be written as P2 = a3, where P = orbital period and a = semimajor axis of orbit (equal to radius for circular orbits).
P = 11.858 earth years would be the new orbital period and Jupiter has an orbital period of 12 years, so this would be the closest one to Earth's new calculated orbital period
Where did the Perseverance rover land? Why was this site chosen? What is Perseverance's primary mission? How is it going?
The Perseverance rover landed on the Jezero Crater (chosen by NASA). They chose this site because scientists believe that the Jezero Crater was once flooded with water, home to an ancient river delta, and they wanted to explore that more (perhaps in the hope to find liquid water). The rover is currently searching for past life on Mars while simultaneously collecting soil and rock samples to one day return to Earth. So far, these samples have not been returned but it is continuing to move uphill and examine more rocks on the surface for evidence of past life on Mars.
Why do planetary scientists think there is an ocean hiding under the icy surface of Europa? If this is true, why isn't the ocean on the surface, where any self-respecting ocean should be (like on the Earth)?
Planetary scientists think there is an ocean under the icy surface of Europa because of its surface features and thermal activity. Europa's surface shows a network of cracks, ridges, and disruptions and these features suggest a dynamic subsurface, which indicates that the icy shell has been shifting and moving. This points to the possibility of an ocean beneath the surface that is causing these movements. There are also observations of heat signatures in certain areas of Europa's surface that imply there might be regions where warmer material is rising from the interior. This is linked to potential hydrothermal activity, which is similar to Earth's ocean vents, possibly showing an ocean under Europa's surface. The ocean is not on the surface because of Europa's icy crust. The surface ice is estimated to be very thick which acts as a barrier between the ocean and the vacuum of space. This thick shell insulates the ocean, painting it as a liquid state despite the cold temperatures on Europa. In all, the geological activity, likely driven by tidal forces from Jupiter's gravity, constantly reforms and resurfaces the icy crust, which prevents the ocean from being exposed.
There are two basic techniques for determining the age of a planetary surface: determining the abundance of impact craters ("crater counting") and radiometric dating of surface rocks (if you can get them back to a lab). Which technique is more reliable? Which technique is more practical? Explain
Radiometric dating of surface rocks is more reliable. This is because it relies on a constant rate of radioactive decay over time and allows for the rocks to be sampled and analyzed. However, this technique is not as practical because it requires the collection of rocks, which is a mass number to go through for planetary exploration missions. Crater counting, however, is more practical because it does not require the collection of any objects. It can be performed remotely using data, but it is less reliable because it is a relative dating method, so there are never exact results of the exact age
(Ch 10 Visual Skills Check) Which physical mechanism is consistent with your answer in the question above (i.e. The variations occur regularly every year based on the graph)?
Seasonal changes in plant growth produce a regular yearly variant in CO2 levels, with the Northern Hemisphere causing almost all the variation. This shows that because there are regular plant growth changes (meaning they take in more CO2 in the spring as more plants are rapidly growing), there are also regular CO2 changes each year.
Name three important reasons why the U.S. was actually able to accomplish this technological and engineering feat.
The U.S. was actually able to accomplish this technological and engineering feat because of Albert the monkey sent into space (U.S. was the first ever to do this), Mercury-Atlas (John Glenn orbits the Earth twice and became national hero), and the Gemini mission (carried a two-astronaut crew rather than one). These helped America gain confidence in their ability to travel space, as well as make the space suits and rocket that would allow them to accomplish this. Moreover, it depended on the vision of its political leaders, intelligence of its scientists, and deviation of its engineers
(Ch 3 Visual Skills Check) On Figure 1, you can see Kepler's third law (p^2 = a^3) from the fact that:
The data falls on a straight line.
What evidence tells us that Venus was "repaved" about 500 million years ago? What might account for the lack of plate tectonics on Venus?
The evidence that tells us that Venus was repaved about 500 million years ago is the lack of craters and the volcanic features. If Venus' surface was older there would be more craters on it, so the lack of these craters suggests a repaving. The volcanic features such as volcanic plains and lava domes indicate that volcanic activity played a role in the repaving of the planet. The absence of plate tectonics on Venus might be due to its thick and stagnant lithosphere, potentially inhibiting the kind of plate movements seen on Earth, leading to a different tectonic regime.
Describe the leading hypothesis for how Mars lost atmospheric gas. What role does Mars's size play in this process?
The leading hypothesis for how Mars lost its atmospheric gas is through solar wind and radiation, and this loss was enough to transform the entire climate on Mars. The solar wind particles from the sun wiped out Mars's atmosphere over years, and its small size played a role in this. Because of its small size, it cools faster and because of this cooling, the metal in its core slowed down until it stopped moving completely, weakening and ultimately making the magnetic field disappear.
What do we mean by the protosolar nebula? What was it made of and what did it come from?
The protosolar nebula is a cloud of gas and dust that astrophysicists believe where our solar system was formed. The protosolar nebula was made of gasses such as helium and hydrogen and various dust particles, and it is thought to have come from giant molecular clouds in deep space.
Very briefly explain how each of the following geological features of the Earth is formed: the seafloor, ocean islands, and mountain ranges
The seafloor is formed through seafloor spreading; this is when magma rises from the Earth's mantle at mid-ocean ridges, which then creates oceanic crust which then forms the seafloor. Ocean islands are formed through volcanic activity because they originate from hotspots; magma rises through the Earth's crust and creates a volcanic island. Over time repeated eruptions build up these islands to create the land we see today. Mountain ranges are formed through continental tectonic plate interactions; this is when two plates collide and they compress and uplift the Earth's crust, which creates these mountain ranges today
Why are seasons on Uranus so extreme?
The seasons on Uranus are so extreme because of its extreme and unique axis tilt. The tilt is about 98 degrees, so it is practically spinning on its side. This means that part of the year on Uranus is dealing with the sun shining directly on one pole for a long hot summer, while the other part of the planet is in a long and very frigid winter.
The major way in which we learn about Earth's interior is through a) drilling deep into the Earth's crust; b) studying seismic waves, or c) spacecraft imagery? Pick the best answer, and explain.
The study of seismic waves is the major way we learn about Earth's interior. Scientists analyze seismic waves when earthquakes occur because they pass through the Earth's layer; this allows them to get information about the interior of Earth. Then, it is possible to learn about the composition, structure, and density of the interior.
What is the sunspot cycle? Why is it sometimes described as an 11-year cycle and sometimes as a 22-year cycle? What cause these changes in solar activity, in a general sense (see textbook)?
The sunspot cycle is a recurring pattern of changes in solar activity. It is sometimes described as an 11-year cycle and sometimes as a 22-year cycle because the 22-year cycle consists of two regular cycles and the reversal of the Sun's magnetic polarity occurs every 22 years. The 11-year cycle is characterized by variation in the amount of sunspots on the Sun's surface. These changes in solar activity are generally driven by the Sun's magnetic field, and these changes in the Sun's magnetism produce a greater number of sunspots, more energy, and cause solar eruptions of particles. The solar cycle is also caused by the sun's rotation and convection, as well as its magnetic field.
(Ch 10 Visual Skills Check) How would you describe the rapid variations of CO2 (which look like "wiggles") on the inset graph?
The variations occur regularly every year based on the upper graph, because there is a constant change in up and down movements (the red line) between the years 1960 and 2020. This conveys regular change in CO2 with it constantly slightly increasing then decreasing every year
(Ch 10 Visual Skills Check) Compare the graphs, which show global temps from 1880 (focus on the period since about 1960). Compare what you notice about the temperatures to what you've learned about carbon dioxide levels - which of the following statements best describes the relationship?
The warmest years correlate roughly with the years of greatest CO2 abundance, indicating that CO2 is important but other factors also contribute to global temperature changes. In figure 10.39, the increase in global temperature since 1960 is gradually increasing, but not at as steady as the rate of the CO2 abundance. This means that CO2 is partly correlated, but not the single factor. If it were the single factor, there would be a direct correlation with not as much fluctuation
(Ch 10 Visual Skills Check) Based on the graph, when was the maximum abundance of CO2 over the past 800,000 years?
There is a rapid spike of CO2 abundance from about 25 thousand years ago until where the graph says "today," making this the maximum abundance of CO2 based on the graph
Mercury has, in a few places randomly scattered about the planet, sinuous channels that look like they were carved by a flowing fluid. Do you think these channels could have been made by flowing water? Explain. Hint: there is water ice in the craters at Mercury's poles. Can you think of another fluid that might have done the job?
These channels could not have been made by flowing liquid water because of the high temperature on Mercury because of its distance from the Sun and its low atmospheric pressure. Another flued that might have done this job is lava, however, because Mercury has a history of volcanic activity. Therefore, the flow of lava could have caused these sinuous channels.
A solar system has been discovered that has 9 planets that all orbit the star in approximately the same plane. However, five planets orbit in one direction (for example, counterclockwise), while the other four orbit in the opposite direction (clockwise). Based on what we know about planet formation, would this discovery be considered reasonable, or implausible?
This discovery would be considered implausible because the laws of that solar system would go against our current understanding of planet formation. This formation is grounded in the laws of physics, angular momentum conservation, and the solar nebular theory, so it is not possible for planets to orbit in the opposite direction because they would perpetually be in retrograde which would destabilize them over time.
If I told you that the Chinese lunar sample return mission from 2020 brought back rocks from an impact crater (from the cooled impact melt on the crater floor) that were subsequently radiometrically dated, and the date turned out to be 50 ± 15 million years old, do you think this would be geologically reasonable or not, and why or why not? If it were true, name a visual characteristic of the crater might corroborate this date (in the sense of being consistent)?
This would not be geologically reasonable because the information we have about the geological processes and history of the moon indicate that most of the craters are at least a billion years old. This means that if this were true, a visual characteristic of the crater that might corroborate this would be the presence of young surface features inside the said crater, like sharp-edges and having debris from impact.
Typical motions on Earth of one plate relative to another are 4 centimeters per year. At this rate, how long would it take for two continents 6000 kilometers apart to collide, that is, if they were moving towards one another? Show your work. (By the way, New York City and London, England, are about 5500 km apart.) If two plates were indeed converging, what important geological or topographic feature would absolutely have to exist somewhere between them? Explain.
To figure out how long it would take for two continents to collide you would use the formula: Time = Distance / Relative Motion Rate - Time = 6000km / (4cm a year) - Need to convert km to cm: 6000km = 6000 times 100000 cm/km = 600000000 cm - Time = 600000000 cm / 4cm/year = 150000000 years - It would take around 150,000,000 years for two continents 6000 kilometers apart to collide if they were moving towards one another at a rate of 4 centimeters per year. If two plates were converging, a subduction zone would be the topographic feature that would have to exist between them. A subduction zone is a plate boundary where one tectonic plate is forced beneath another; it would have to exist because a subduction zone is the consequence of the collision between two plates of differing densities.
We determine the temperature of the surface of the Sun by measuring its radiation as a function of wavelength and comparing it to what law(s) or formula(s)? In contrast, we estimate the temperature at the center of the Sun using which of the following: (a) probes that measure changes in Earth's atmosphere; (b) mathematical models based on nuclear physics and the laws of radiation transport; (c) laboratories that create miniature versions of the Sun.
We determine the temperature of the Sun and compare it to Planck's law of blackbody radiation. We estimate the temperature of the sun by using mathematical models based on nuclear physics and the laws of radiation transport (B). This is because these mathematical models use calculations from various formulas to provide the most accurate estimation of the temperature at the center of the Sun.
Name three important reasons why President Kennedy committed (or asked Congress to commit) the U.S. to landing a man on the Moon and returning him safely to the Earth.
When John F. Kennedy was elected to the presidency, it was a new era for America, and the United States could not simply play "catch up" with the Soviet Union; Kennedy found it unacceptable that the U.S. would be second best. With our industrial base and optimistic society, Kennedy decided to set America's hopes on something near enough and conceivable, so he committed himself to going to the moon by the end of the century. Space was the symbol of the 20th century, and the sense of vibrancy and national will with a program like this would embody the American spirit. Apollo ended up being a focus for national development after this was accomplished.
(more questions from homework #4 but they are math so review those)
X
Would Mars still have seasons even if its elliptical orbit around the Sun were perfectly circular rather than elliptical? Explain. Note that Mars' eccentricity does oscillate over time, and every 4 million years or so gets quite close to zero.
Yes, Mars would still experience seasons even if its orbit were perfectly circular. Seasons on Mars are primarily influenced by its axial tilt, similar to how Earth experiences seasons. Mars has an axial tilt of about 25 degrees, which is similar to Earth's 23.5 degrees. Mars' eccentricity affects its distance from the Sun during orbit but does not significantly alter the seasons. The axial tilt is the reason for the seasons because as it orbits, different parts receive different amounts of sunlight. While the eccentricity of Mars' orbit does play a role in the intensity of the seasons (how extreme they are), a circular or near-circular orbit wouldn't eliminate the existence of seasons (although it may moderate the differences between the seasons by making the amount of sunlight received more consistent throughout the orbit)
(Ch 3 Visual Skills Check) Approximately how fast is Jupiter orbiting the Sun?
a little less than 15 km/s.
(Ch 9 Visual Skills Check) Using the answers from ch 9 visual skills check above, list the following features in order from oldest to youngest: tectonic ridge from 3a to 3b crater 1a the smooth floor of crater 1b
crater 1a → the smooth floor of crater 1b → the tectonic ridge from 3a to 3b. This is oldest to youngest as explained in parts A-C, where crater 1a formed before crater 1b and the tectonic ridge formed last because it is still very visible
(Ch 8 Visual Skills Check) You find a mysterious rock on the ground and determine that 60% of its uranium-235 has been converted into lead-207. What is the most likely origin of the rock, based on its radiometric age?
it's a volcanic rock nearly a billion years old.
(Ch 2 Visual Skills Check) The diagram exaggerates the sizes of Earth and the Sun relative to the orbit. If Earth were correctly scaled relative to the orbit in the figure, how big would it be?
microscopic
Choose one property of Earth — either size, distance from the Sun, or rotation rate — and suppose that it had been significantly different. Describe how this change might have affected Earth's subsequent geological history and the possibility of our existence today on Earth
rotation rate : If the rotation rate were faster, we would have shorter days and nights. This would also lead to stronger Coriolis forces (similar to Jupiter's), which impacts ocean currents and weather patterns. The centrifugal force from the faster rotation might also alter the planet's shape which could cause changes in volcanic activity and tectonic plate movement (might make the planet less spherical). Regarding the possibility of our existence, life may have evolved differently with shorter days and nights as plants and animals would adapt to quicker changes between light and dark. If the rotation rate were slower, we would have longer days and nights. This may lead to extreme temperature variations between the days, which would impact weather patterns, as more sunlight could lead to intense heat and longer cooling periods at night, subsequently affecting ocean currents and flora and fauna. Regarding the possibility of our existence, we would have adapted differently to cope with the extended periods of day and night. Plants may evolve to endure longer exposure and to conserve energy, and animal behavior would also have evolved differently to deal with prolonged day or darkness (different adaptive mechanisms than we see today).
(Ch 10 Visual Skills Check) Today's CO2 abundance is approx ______ times the average value over the last 800,000 years.
the abundance of CO2 today is about 425 ppm, and the average (based on the graph) is around 250 ppm. 425/250 = 1.7, which is the closest to 1.8 from the answer options.
(Ch 2 Visual Skills Check) Given that Earth's actual distance from the Sun varies less than 3% over the course of a year, why does the diagram look so elliptical?
the elliptical shape is an effect of perspective, since the diagram shows an almost edge-on view of a nearly circular orbit.
(Ch 3 Visual Skills Check) Kepler's third law is often stated as p^2 = a^3. The value a^3 for a planet is shown on:
the horizontal axis of graph a
