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126 Cards in this Set
- Front
- Back
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Which of the following statements about our Sun is NOT true?
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The Sun's diameter is about five times that of Earth.
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The planet in our solar system with the highest average surface temperature is __________
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venus |
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Which jovian planet does NOT have rings?
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All the jovian planets have rings |
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What is the Kuiper belt?
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a region of the solar system beginning just beyond the orbit of Neptune that contains many icy comets
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Which of the following statements about Pluto is true?
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It has more in common with comets in the Kuiper belt than it does with terrestrial planets like Earth.
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Suppose you view the solar system from high above Earth's North Pole. Which of the following statements about planetary orbits will be true?
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All the planets orbit counterclockwise around the Sun.
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When we say that jovian planets contain significant amounts of hydrogen compounds, we mean all the following chemicals EXCEPT ______.
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carbon dioxide |
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What is the Oort cloud?
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It's not really a cloud at all, but rather refers to the trillion or so comets thought to orbit the Sun at great distances.
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In essence, the nebular theory holds that _________.
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our solar system formed from the collapse of an interstellar cloud of gas and dust
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What do we mean by the frost line when we discuss the formation of planets in the solar nebula?
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It is a circle at a particular distance from the Sun, beyond which the temperature was low enough for ices to condense.
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According to our theory of solar system formation, what three major changes occurred in the solar nebula as it shrank in size?
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It got hotter, its rate of rotation increased, and it flattened into a disk.
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What is the giant impact hypothesis for the origin of the Moon?
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The Moon formed from material blasted out of Earth's mantle and crust by the impact of a Mars-size object.
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According to modern scientific dating techniques, approximately how old is the solar system?
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4.5 billion years |
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Which of the following types of material can condense into what we call ice at low temperatures?
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hydrogen compounds
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According to our theory of solar system formation, what are asteroids and comets?
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leftover planetesimals that never accreted into planets
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Suppose you start with 1 kilogram of a radioactive substance that has a half-life of 10 years. Which of the following statements will be true after 20 years pass?
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You'll have 0.25 kilogram of the radioactive substance remaining.
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Our Moon is about the same size as moons of the other terrestrial planets.
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false |
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On average, Venus is the hottest planet in the solar system - even hotter than Mercury.
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true |
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What's unusual about our Moon?
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It’s surprisingly large relative to the planet it orbits.
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Based on your study of the Interactive Figure, which of the following is not one of the four major features of the solar system?
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The solar system contains eight planets plus dwarf planets (including Ceres, Pluto, and Eris).
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The solar system contains vast numbers of small bodies, which we call asteroids when they are rocky and comets when they are icy. These small bodies are concentrated in the region(s) of the solar system that we call __________.
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The Ooort cloud The asteroid belt The kuiper belt |
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Consider only the observed patterns of motion in the solar system. Scientifically, which of the following possible conclusions is justified from the patterns of motion alone?
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The planets were not each born in a separate, random event.
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Now consider why the observed patterns of motion lead to the conclusion that the planets were not born in separate, random events. The reason for this conclusion is that, if the planets had been born in separate, random events, we would expect that __________.
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planetary orbits would have many different orientations and directions, rather than all being in the same direction and in the same plane
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Today, scientists have a theory (the nebular theory) that explains all the major characteristics of the solar system. In science, we expect a theory like this not only to explain the observed characteristics of our solar system but also to __________.
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make testable predictions about other solar systems
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The mass of the Sun compared to the mass of all the planets combined is like the mass of an elephant compared to the mass of a cat.
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true |
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The weather conditions on Mars today are much different than they were in the distant past.
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true |
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Moons cannot have atmospheres, active volcanoes, or liquid water.
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false |
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Saturn is the only planet in the solar system with rings.
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false |
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Which terrestrial planets have had volcanic activity at some point in their histories?
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all of them |
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Large moons orbit their planets in the same direction the planet rotates:
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Most of the time |
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Pluto orbits the Sun in the opposite direction of all the other planets.
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false |
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How many of the planets orbit the Sun in the same direction that Earth does?
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all of them |
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What fraction of the moons of the planets orbit in the same direction that their planets rotate?
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most |
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When the solar nebula was about 4000 AU in radius, how fast would the same material have orbited? (Remember that when the cloud was larger, motions were more random, so we can calculate only the average.) Use the law of conservation of angular momentum (see Section Conservation Laws in Astronomy).
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v≈50m/s
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Observations show that interstellar clouds can have almost any shape and, if they are rotating at all, their rotation is not perceptible. However, as shown in the animation, the nebular theory predicts that a cloud will rotate rapidly once it shrinks to a small size. What physical law explains why a cloud will rotate rapidly as it collapses?
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the law of conservation of angular momentum
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The nebular theory also predicts that the cloud should heat up as it collapses. What physical law explains why it heats up?
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the law of conservation of energy
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The nebular theory also predicts that the cloud will flatten into a disk as it shrinks in size. Which of the following best explains why the collapsing cloud should form a disk?
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Colliding cloud particles exchange angular momentum and, on average, end up with the rotation pattern for the cloud as a whole.
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As you've seen, the nebular theory predicts that a cloud that gives birth to planets should have the shape of a spinning disk. Which observable property of our solar system supports this prediction?
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All the planets orbit the Sun in the same direction and in nearly the same plane.
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The solar system has two types of planets, terrestrial and jovian. According to the nebular theory, why did terrestrial planets form in the inner solar system and jovian planets in the outer solar system?
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Ices condensed only in the outer solar system, where some icy planetesimals grew large enough to attract gas from the nebula, while only metal and rock condensed in the inner solar system, making terrestrial planets.
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What is Jupiter's main ingredient?
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hydrogen and helium |
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Which lists the major steps of solar system formation in the correct order?
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collapse, condensation, accretion
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Leftover ice-rich planetesimals are called
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comets |
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Why didn't a terrestrial planet form at the location of the asteroid belt?
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Jupiter's gravity kept planetesimals from accreting.
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What substances were found within the inner 0.3 AU of the solar system before planets began to form?
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rocks, metals, hydrogen compounds, hydrogen, and helium, all in gaseous form
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What substances existed as solid flakes within the inner 0.3 AU of the solar system before planets began to form?
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none |
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Where would you expect terrestrial planets to form in the solar nebula?
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anywhere between 0.3 AU and the frost line
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The jovian planets are thought to have formed as gravity drew hydrogen and helium gas around planetesimals made of __________.
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rocks, metals, and ices
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Two hypothetical discoveries in Part A deal with moons that, like Earth's moon, are relatively large compared to their planets. Which of the following best explains why finding 1 planet with such a moon is consistent with the nebular theory, while finding 6 planets with such moons is not consistent?
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Unusually large moons form in giant impacts, which are relatively rare events.
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Consider the hypothetical discovery from Part A reading: "A star's 5 terrestrial planets orbit in the opposite direction of its 3 jovian planets." This discovery would be inconsistent with the nebular theory because the theory holds that __________.
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all the planets formed in a rotating, disk-shaped nebula
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Consider the hypothetical discovery from Part A reading: "Beyond its jovian planets, a star has two ice-rich objects as large as Mars." This discovery is consistent with the nebular theory, because this theory predicts that _________.
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this might have happened in our own solar system if it had taken longer for the solar wind to clear the solar nebula
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What’s the leading theory for the origin of the Moon?
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It formed from the material ejected from Earth in a giant impact.
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Assuming that other planetary systems form in the same way as our solar system formed, where would you expect to find terrestrial planets?
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Terrestrial planets will likely be located nearer the planetary system’s star than any jovian planets.
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Compared to terrestrial planets, jovian planets are __________.
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more massive and lower in average density
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Which planet is approximately halfway between Pluto’s orbit and the Sun?
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Uranus, the seventh planet from the Sun
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Which of the following is not a major pattern of motion in the solar system?
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Nearly all comets orbit the Sun in same direction and roughly the same plane.
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Which of the following is not a major difference between the terrestrial and jovian planets in our solar system?
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Terrestrial planets contain large quantities of ice and jovian planets do not.
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Consider the following statement: "Rocky asteroids are found primarily in the asteroid belt and Kuiper belt while icy comets are found primarily in the Oort cloud." What's wrong with this statement?
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The Kuiper belt contains icy comets, not rocky asteroids.
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Which of the following is not a real difference between asteroids and comets?
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Asteroids orbit the Sun while comets just float randomly around in the Oort cloud.
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The following statements are all true. Which one counts as an "exception to the rule" in being unusual for our solar system?
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The diameter of Earth's Moon is about 1/4 that of Earth
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Compared to the distance between Earth and Mars, the distance between Jupiter and Saturn is ______.
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much larger |
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How is Einstein's famous equation, E=mc 2, important in understanding the Sun?
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It explains the fact that the Sun generates energy to shine by losing some 4 million tons of mass each second.
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Venus has a higher average surface temperature than Mercury. Why?
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Because its surface is heated by an extreme greenhouse effect.
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In what way is Venus most similar to Earth?
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Both planets are nearly the same size.
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Which of the following statements about the object called Eris is not true?
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It is thought to be the first example of a new class of object.
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Mars has two moons that are most similar in character to:
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small asteroids |
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Imagine that an alien spaceship crashed onto Earth. Which statement would most likelybe true?
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it would crash in the ocean |
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Which planet listed below has the most extreme seasons?
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uranus |
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In what way is Pluto more like a comet than a planet?
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it is made mostly of rock and ice |
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Why was it advantageous for the Voyager mission to consist of flybys rather than orbiters?
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Each individual spacecraft was able to visit more than one planet.
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Why has NASA sent recent orbiters to Mars (such as Mars Reconnaissance Orbiter) on trajectories that required them to skim through Mars's atmosphere before settling into their final orbits?
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It saves money because the spacecraft uses atmospheric drag to slow down rather than needing to carry enough fuel to slow by firing rocket engines.
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This photo shows a "debris disk" around a nearby star. What is the significance of this type of "debris disk"?
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It shows that stars really can be surrounded by flattened disks of dust and gas.
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This painting shows an object colliding with Earth. What is thought to have happened as a result of this collision?
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It blasted away debris that then accreted in Earth orbit to form the Moon.
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Which of the following best explains why we can rule out the idea that planets are usually formed by near-collisions between stars?
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Stellar near-collisions are far too rare to explain all the planets now known to orbit nearby stars.
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According to our modern science, which of the following best explains why the vast majority of the mass of our solar system consists of hydrogen and helium gas?
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Hydrogen and helium are the most common elements throughout the universe, because they were the only elements present when the universe was young.
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According to our theory of solar system formation, which law best explains why the central regions of the solar nebula got hotter as the nebula shrank in size?
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The law of conservation of energy
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According to our theory of solar system formation, which law best explains why the solar nebula spun faster as it shrank in size?
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The law of conservation of angular momentum
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According to our present theory of solar system formation, which of the following best explains why the solar nebula ended up with a disk shape as it collapsed?
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It flattened as a natural consequence of collisions between particles in the nebula.
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What is the primary basis upon which we divide the ingredients of the solar nebula into four categories (hydrogen/helium; hydrogen compound; rock; metal)?
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The temperatures at which various materials will condense from gaseous form to solid form.
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According to our present theory of solar system formation, which of the following statements about the growth of terrestrial and jovian planets is not true?
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The jovian planets began from planetesimals made only of ice, while the terrestrial planets began from planetesimals made only of rock and metal.
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Many meteorites appear to have formed very early in the solar system's history. How do these meteorites support our theory about how the terrestrial planets formed?
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The meteorites appearance and composition is just what we'd expect if metal and rock condensed and accreted as our theory suggests.
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According to present understanding, which of the following statements about the solar wind is not true?
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It is even stronger today than it was when the Sun was young.
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According to our present theory of solar system formation, how did Earth end up with enough water to make oceans?
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The water was brought to the forming Earth by planetesimals that accreted beyond the orbit of Mars.
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What is the primary reason that astronomers suspect that some jovian moons were captured into their current orbits?
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Some moons have orbits that are "backwards" (compared to their planet's rotation) or highly inclined to their planet's equator.
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Which of the following is not a line of evidence supporting the hypothesis that our Moon formed as a result of a giant impact?
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The Pacific Ocean appears to be a large crater - probably the one made by the giant impact.
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Why are terrestrial planets denser than jovian planets?
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Only dense materials could condense in the inner solar nebula.
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Suppose you find a rock that contains 10 micrograms of radioactive potassium-40, which has a half-life of 1.25 billion years. By measuring the amount of its decay product (argon-40) present in the rock, you conclude that there must have been 80 micrograms of potassium-40 when the rock solidified. How old is the rock?
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3.75 billion years |
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How do scientists determine the age of the solar system?
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Radiometric dating of meteorites
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The region of our solar system between Mercury and Mars has very few asteroids, while the region between Mars and Jupiter has many asteroids. Based on what you have learned, what is the most likely explanation for the lack of asteroids between Mercury and Mars?
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There were very few planetary leftovers in this region, because most of the solid material was accreted by the terrestrial planets as the planets formed.
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About 2% of our solar nebula consisted of elements besides hydrogen and helium. However, the very first generation of star systems in the universe probably consistedonly of hydrogen and helium. Which of the following statements is most likely to have been true about these first-generation star systems?
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There were no comets or asteroids in these first-generation star systems.
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What is an extrasolar planet?
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a planet that orbits a star that is not our own Sun
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The first confirmed detections of extrasolar planets occurred in ____________
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the 1990s |
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Based on available data, what kind of objects in our solar system do most of the known extrasolar planets resemble?
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Jovian planets |
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Which new idea has been added into our theory of solar system formation as a result of the discoveries of extrasolar planets?
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Jovian planets can migrate from the orbits in which they are born.
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Which detection techniques can find the planet's orbital distance (assuming we know the mass of the star)?
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all of these techniques |
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Why do we say that the Doppler technique gives the planet's "minimum mass"?
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The size of the Doppler shift that we detect depends on whether the planet's orbit is tilted.
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How do we use velocity curves (obtained from spectroscopy) to show that some extrasolar planets are close to their host stars?
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The velocity curve of the host star shows periods much shorter than a year.
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Which of the following orbital characteristics has NOT been observed among any known extrasolar planets?
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orbital speeds that are so slow that we cannot explain them orbits that are not elliptical |
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What method has detected the most extrasolar planets so far?
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the Doppler technique
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Which one of the following can the transit method tell us about a planet?
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its size |
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Which method could detect a planet in an orbit that is face-on to the Earth?
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Astrometric technique |
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Most extrasolar planets discovered so far most resemble
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jovian planets |
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Most known extrasolar planets are more massive than Jupiter because
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current detection methods are more sensitive to larger planets.
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Which of the following properties can be inferred from the star’s orbital period?
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the planet's orbital radius |
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Is it possible to determine the planet's mass from the star's velocity curve?
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yes, by measuring both the star's orbital period and its change in velocity over the orbit
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Consider the planet that causes the stellar motion shown in Plot 2 (be sure you have clicked the “Plot 2” button in the lower window of the animation). What can be said about a different planet orbiting the same star with an orbital period of 500 days?
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The planet must be closer to the star.
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Based on what we know about our own solar system, the discovery of hot Jupiters came as a surprise to scientists because these planets are __________.
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so close to their stars |
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Our modern theory of solar system formation—the nebular theory—successfully accounts for all the major features of our own solar system. However, when the first hot Jupiters were discovered, their existence seemed inconsistent with the nebular theory because this theory predicts that __________.jovian planets located close to their stars should have evaporated by nowany system with jovian planets should also have terrestrial planetsjovian planets can form only in the cold, outer regions of a solar systemplanetary systems should be extremely rare
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jovian planets can form only in the cold, outer regions of a solar system
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How is the planet 51 Pegasi different from Jupiter?
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much closer to its star |
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Which detection method can be used on a backyard telescope with a CCD system?
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transits |
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Why do scientists say that evolution is a "theory"?
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because it explains a great deal about life and is supported by an enormous body of evidence
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In the Drake equation (Number of Civilizations ≡ N HP × f life × f civ × f now), what do we mean by fnow?
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the fraction of planets with civilizations at the present time (as opposed to only in the past or future)
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Why don't we expect to find life on planets orbiting high-mass stars?
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The lifetime of a high-mass star is too short.
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From the viewpoint of an alien astronomer, how does Jupiter affect observations of our Sun?
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It causes the Sun to move in a small ellipse with an orbital period of about 12 years.
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Why is it so difficult to take pictures of extrasolar planets?
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Their light is overwhelmed by the light from their star.
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Suppose you are using the Doppler technique to look for planets around another star. What must you do?
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Compare many spectra of the star taken over a period of many months or years.
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In general, which type of planet would you expect to cause the largest Doppler shift in the spectrum of its star?
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a massive planet that is close to its star |
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Suppose a planet is discovered by the Doppler technique and is then discovered to have transits. In that case, we can determine all the following about the planet except ______________.
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its rotation period |
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The transit method allows us in principle to find planets around __________.
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only a small fraction of stars that have planets
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Which of the following will allow you to learn something about a transiting planet's atmospheric composition?
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Compare spectra obtained before and during an eclipse.
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Very few of the known extrasolar planets have sizes as small as Earth. The most likely reason for this fact is that ________.
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small planets are more difficult to detect than larger planets
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Based on everything you have learned about the formation of our solar system, which of the following statements is probably not true?
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Only a tiny percentage of stars are surrounded by spinning disks of gas during their formation.
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When is the soonest we are likely to have moderate-resolution images and spectra of Earthlike planets around other stars? |
In a decade or two, through space observatories now in the early planning stages.
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Earth was born about 4.5 billion years ago. According to current estimates, approximately how long after Earth’s formation did the Moon form?
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a few hundred million years later |
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The oldest fossil evidence of life dates to about __________ ago.
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3.5 to 4 billion years
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Dinosaurs went extinct, probably because of an impact, about __________ ago.
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65 million years |
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Which statement explains the observations that make it seem possible that Mars could have life underground?
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We have detected water ice on Mars, and Mars still has some volcanic heat.
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