Astrobiology PHYS 13: Chpt 2

Any spectrum can be displayed either in photographic form as shown to the left or as a graph. Which of the following graphs could represent a portion of the Sun's visible light spectrum? View Available Hint(s) The plot shows intensity as a function of wavelength. No units are given for both x and y axes. The graph is a smooth concave down curve. It starts at the point that lies on the y-axis, at about 0.75 of the y-axis range, and slightly increases, then it reaches its maximum and starts to decrease. The increasing part of the graph is about 0.6 of the x-axis range. The plot shows intensity as a function of wavelength. No units are given for both x and y axes. The graph is a smooth concave down curve. It starts at the point that lies on the y-axis, at about 0.75 of the y-axis range, and slightly increases, then it reaches its maximum and starts to decrease. The increasing part of the graph is about 0.6 of the x-axis range. There are 11 acute peaks directed downward from this curve to the x-axis. The plot shows intensity as a function of wavelength. No units are given for both x and y axes. The graph is a series of 11 acute peaks, directed upward from the x-axis. The maximum values of the peaks are smoothly increasing for the first 4 peaks, and then they are smoothly decreasing.

(It's the middle one) The smooth part of the curve represents the graph of the background rainbow of color; the dips in the curve represent the black lines where light is missing from the rainbow.

Consider the indicated events in the history of the universe that have helped make human life possible. Rank the events based on when they occurred, from longest ago to most recent. To rank items as equivalent, overlap them. Note: If two events occurred within seconds of each other, rank them as equivalent. A) Big Bang B) nuclear fusion begins in the Sun C) elements such as carbon and oxygen first exist D) earliest humans E) earliest life on Earth F) the universe beings expand G) dinosaurs go extinct

1) Big bang & the universe beings to expand 2) elements such as carbon and oxygen first exist 3) nuclear fusion begins in the Sun 4) earliest life on Earth 5) dinosaurs go extinct 6) earliest humans Now that you know the order in which these events occurred, continue on to check whether you know approximately when they occurred.

Provided following are stages that occurred during the formation of our solar system. Rank these stages from left to right based on when they occurred, from first to last. A) large cloud of gas and dust B) contraction of solar nebula C) condensation of solid particles D) accretion of planetesimals E) clearing the solar nebula

1) large cloud of gas and dust 2) contraction of solar nebula 3) condensation of solid particles 4) accretion of planetesimals 5) clearing the solar nebula Once the solar wind helped clear away the remaining gas in the solar nebula, the era of planet formation was essentially over. Remember that all these stages occurred over a period of millions of years, ending about 4 1/2 billion years ago.

Comte was proven wrong in his claim that we could never learn the composition of stars. What do we know today that Comte did not know when making his claim, and that makes it possible for us to learn the chemical compositions of stars? A) Every chemical element produces a unique spectral fingerprint. B) Stars emit not only visible light, but also other forms of light including infrared, ultraviolet, and X-rays. C) Sunlight is made from a combination of colors that can be spread out into a spectrum. D) Telescopes tend to become larger and more powerful with time.

A) Every chemical element produces a unique spectral fingerprint. If Comte had known that every element leaves a unique spectral fingerprint on light, he presumably could have guessed that we'd ultimately learn the chemical compositions of stars.

From shortest to longest wavelength, which of the following correctly orders the different categories of electromagnetic radiation? A) Gamma rays, X rays, ultraviolet, visible light, infrared, radio B) Infrared, visible light, ultraviolet, X rays, gamma rays, radio C) Radio, infrared, visible light, ultraviolet, X rays, gamma rays D) Gamma rays, X rays, visible light, ultraviolet, infrared, radio

A) Gamma rays, X rays, ultraviolet, visible light, infrared, radio This is also the order from highest to lowest energy, and from highest to lowest frequency.

The table in the video shows you the speeds of Raisins 1, 2, and 3 as measured from the Local Raisin. Suppose instead that you measured speeds as seen from Raisin 2. An observer at Raisin 2 would measure __________. View Available Hint(s) A) Local Raisin speed = 4.0 cm/hr; Raisin 1 speed = 2.0 cm/hr; Raisin 3 speed = 2.0 cm/hr B) Local Raisin speed = 6.0 cm/hr; Raisin 1 speed = 4.0 cm/hr; Raisin 3 speed = 2.0 cm/hr C) Local Raisin speed = 2.0 cm/hr; Raisin 1 speed = 4.0 cm/hr; Raisin 3 speed = 6.0 cm/hr D) Local Raisin speed = 4.0 cm/hr; Raisin 1 speed = 2.0 cm/hr; Raisin 3 speed = 4.0 cm/hr E) Local Raisin speed = 2.0 cm/hr; Raisin 1 speed = 2.0 cm/hr; Raisin 3 speed = 2.0 cm/hr

A) Local Raisin speed = 4.0 cm/hr; Raisin 1 speed = 2.0 cm/hr; Raisin 3 speed = 2.0 cm/hr Note that the observer at Raisin 2 sees essentially the same thing as the observer at the Local Raisin: The nearest raisins (Raisins 1 and 3 in this case) are moving away at 2 cm/hr and the next nearest (the Local Raisin in this case) is moving away at 4 cm/hr. If the cake were bigger, the pattern would continue. The key point is this: It does not matter which raisin you observe from; in an expanding raisin cake — or an expanding universe — all observers see all the other raisins (galaxies) moving away, with more distant raisins (galaxies) moving faster.

What are four key features of our solar system that any theory of solar system formation must be able to explain? Select exactly four responses. A) Planets fall into two major categories. B) The Sun generates energy through fusion of hydrogen into helium. C) There are a few notable "exceptions to the rules." D) There are vast numbers of asteroids and comets. E) The solar nebula collapsed due to gravity. F) There are clear patterns to the rotation and orbits of large bodies in the solar system.

A) Planets fall into two major categories. C) There are a few notable "exceptions to the rules." D) There are vast numbers of asteroids and comets. F) There are clear patterns to the rotation and orbits of large bodies in the solar system. As discussed in the video, these four features are all successfully explained by the nebular theory.

For the purposes of seeking a theory to explain the formation of the solar system, we identify four major features of our solar system. Which of the following represent these four major features? Select four statements to represent the four features. A) Several exceptions to the general trends stand out. B) Large bodies in the solar system have orderly motions. C) Swarms of asteroids and comets populate the solar system. D) The solar system contains eight planets plus dwarf planets (such as Ceres, Pluto, and Eris). E) The largest planet, Jupiter, has a mass greater than all the other planets combined. F) Planets fall into two major categories (terrestrial and jovian)

A) Several exceptions to the general trends stand out. B) Large bodies in the solar system have orderly motions. C) Swarms of asteroids and comets populate the solar system. F) Planets fall into two major categories (terrestrial and jovian) In the rest of this tutorial, we will explore why these features are important to developing a theory of how our solar system formed.

A carbon atom with six protons and six neutrons will be electrically neutral if it contains ________. A) six electrons B) zero electrons C) twelve electrons D) six molecules

A) six electrons The negative charge of the electrons then balances the positive charge of the protons; the neutrons have no electrical charge.

Out immediately beyond the orbit of the planet Neptune we find A) the Kuiper belt B) the asteroid belt C) the Oort cloud D) Orion's belt

A) the Kuiper belt

The following statements describe ways in which the analogy might apply to the real universe. Which statements are correct? Check all that apply. View Available Hint(s) A) The raisins stay roughly the same size as the cake expands, just as galaxies stay roughly the same size as the universe expands. B) An observer at any raisin sees more distant raisins moving away faster, just as an observer in any galaxy sees more distant galaxies moving away faster. C) Both the raisin cake and the universe have a well-defined inside and outside. D) The average distance increases with time both between raisins in the cake and between galaxies in the universe. E) The temperature starts low and ends high in both the raisin cake and the universe. F) Raisin 1 is near the center of the cake, just as our galaxy is near the center of the universe.

A) The raisins stay roughly the same size as the cake expands, just as galaxies stay roughly the same size as the universe expands. B) An observer at any raisin sees more distant raisins moving away faster, just as an observer in any galaxy sees more distant galaxies moving away faster. and outside. D) The average distance increases with time both between raisins in the cake and between galaxies in the universe. Like any scientific model, the raisin cake analogy has limitations, but it gives us a good overall picture of how the universe is expanding.

All the following statements are true. Which of them are considered to be "exceptions" to the general trends described by the first three major features of the solar system? Check all that apply. A) Venus rotates in a direction opposite to the rotation of the other terrestrial planets. B) Our Moon has a diameter more than 1/4 the diameter of Earth. C) Jupiter's largest moon, Ganymede, is even larger than Earth's moon. D) Uranus rotates with an axis tilt that lies nearly in the ecliptic plane. E) Pluto is in the outer solar system but is ice-rich in composition.

A) Venus rotates in a direction opposite to the rotation of the other terrestrial planets. B) Our Moon has a diameter more than 1/4 the diameter of Earth. D) Uranus rotates with an axis tilt that lies nearly in the ecliptic plane. Note that these exceptions must still be accounted for by any reasonable theory of solar system formation.

A light-year is ________. A) about 10 trillion kilometers B) the speed at which light travels C) an expression used for anything very large D) a year as measured by light

A) about 10 trillion kilometers That is, a light- year is a unit of distance, more specifically it is the distance that light can travel through space in one year.

Visible light is an example of A) an electromagnetic wave B) a seismic wave C) a gravitational wave D) a compression wave

A) an electromagnetic wave

Suppose that someone in the Andromeda galaxy had a super-telescope through which they were looking at Earth right now. They would see Earth ______. A) as it was about 2 ½ million years ago B) as it was about 100,000 years ago C) as it is right now D) as it will be about 2 ½ million years from now

A) as it was about 2 ½ million years ago The approximately 2 ½-million-light-year distance between Earth and the Andromeda galaxy means that light takes about 2 ½ million years to travel this distance. Therefore, just as we see the Andromeda galaxy as it was about 2 ½ million years ago, someone looking right now from Andromeda would see us as we were about 2 ½ million years ago.

The Big Bang predicts that after the universe was born it A) consisted of mostly hydrogen and helium B) consisted of an equal mixture of all the chemical elements C)was completely empty D) consisted of mostly carbon, hydrogen, oxygen and nitrogen

A) consisted of mostly hydrogen and helium

Pluto, Eris and Ceres are all examples of A) dwarf planets B) Kuiper belt objects C) planets D) asteroids

A) dwarf planets

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 predict __________. A) general characteristics of other solar systems B) the exact details of planets and their orbits in all other solar systems C) some major change that will eventually occur in our own solar system D) which planets have life

A) general characteristics of other solar systems A scientific theory must always make testable predictions, because that is the only way we can evaluate the validity of the theory. In the case of a solar system theory, it should successfully explain the general characteristics of other solar systems. Provide Feedback

Which of the following are forms of light (electromagnetic radiation)? Select all that apply. A) infrared B) visible light C) gamma rays D) microwaves E) radio waves F) X rays G) ultraviolet

A) infrared B) visible light C) gamma rays D) microwaves E) radio waves F) X rays G) ultraviolet As explained in your textbook and the video, light is an electromagnetic wave that travels at the speed of light. Therefore all the regions of the electromagnetic spectrum can be thought of as different forms of light.

The term organic molecules generally refers to ________. A) molecules containing carbon B) all molecules involved in life in any way, including iron compounds and water C) molecules grown without pesticides on certified farms D) molecules made from atoms of two or more different elements, such as water

A) molecules containing carbon Most carbon compounds are considered organic (with a few exceptions, such as carbon dioxide).

Compared to the Earth, the universe is A) much older B) just slightly older C) much younger D) about the same age

A) much older

Which subatomic particle or particles have no charge? A) neutrons only B) all subatomic particles have no charge C) electrons and neutrons D) neutrons and protons

A) neutrons only

What substances existed as solid flakes within the innermost regions (within about the inner 0.3 AU) of the solar system before planets began to form? A) none B) only rocks and metals C) only hydrogen compounds D) only hydrogen and helium gases

A) none Although all the materials were present in gaseous form, the innermost regions (within about the inner 0.3 AU) of the newly forming solar system was too warm for even rocks or metals to condense into solid flakes.

The "giant impact hypothesis" refers to the idea that ___________. A) our Moon formed when a Mars-size object collided with the young Earth. B) dinosaur extinction was caused by the impact of an asteroid. C) large craters on the Moon were formed by large impacts. D) the planets formed when another star nearly collided with our Sun.

A) our Moon formed when a Mars-size object collided with the young Earth. Review the video or your textbook for the details of how scientists suspect our Moon formed in a giant impact.

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 __________. Select all that apply. View Available Hint(s) A) the Oort cloud B) the Kuiper belt C) the comet belt D) the solar corona E) the Doppler belt F) the asteroid belt

A) the Oort cloud B) the Kuiper belt F) the asteroid belt Most asteroids are found in the asteroid belt between Mars and Jupiter. Comets are concentrated in two regions: the Kuiper belt just beyond the orbit of Neptune and the much more distant and roughly spherical region known as the Oort cloud.

How does the speed (in a vacuum) of a high-frequency electromagnetic wave compare with a low-frequency electromagnetic wave? A) the two waves have the same speed because the speed of light is constant B) the lower-frequency wave has the higher speed because it has the longest wavelength C) the higher-frequency wave has the higher speed D) the lower-frequency wave has the higher speed because speed is inversely related to frequency

A) the two waves have the same speed because the speed of light is constant

The idea that the universe began in a Big Bang is now well-supported by evidence but initially arose as a logical inference based on the fact that ________. A) the universe is expanding B) the farther away we look into space, the further back we look into time C) the chemical composition of the universe consists mostly of hydrogen and helium D) stars orbit around the centers of their galaxies

A) the universe is expanding This implies that if we go back far enough in time, we must reach a point at which the expansion began, which is the Big Bang.

According to current astronomical data, approximately how old is the universe? A) 4.6 billion years B) 14 billion years C) 65 million years D) 6000 years

B) 14 billion years

Now consider the second major feature (two types of planets). Which of the following statements are true for the terrestrial and jovian planets in our solar system? Select all that apply. View Available Hint(s) A) Jovian planets are made most of metal, rock, and helium. B) Jovian planets have more moons than terrestrial planets. C) Jovian planets orbit farther from the Sun than terrestrial planets. D) Jovian planets are larger in mass than terrestrial planets. E) Jovian planets are larger in size than terrestrial planets.

B) Jovian planets have more moons than terrestrial planets. C) Jovian planets orbit farther from the Sun than terrestrial planets. D) Jovian planets are larger in mass than terrestrial planets. E) Jovian planets are larger in size than terrestrial planets. Note that the characteristics relating to size, mass, and composition are considered to be defining characteristics for the terrestrial and jovian categories; that is, we would identifiy planets in other systems as terrestrial or jovian if they have these same general characteristics. In contrast, while all the jovian planets in our solar system orbit much farther from the Sun than the terrestrial planets, there are other solar systems in which jovian planets have been found to orbit much closer to their stars.

Consider the first major feature (orderly motions). Which of the following correctly describe patterns of motion in our solar system? Select all that apply. A) Inner planets orbit the Sun in the opposite direction from the outer planets. B) The Sun and most of the planets rotate in the same direction that the planets orbit. C) All the planets orbit the Sun in nearly the same plane. D) Planets have nearly circular orbits. E) Major moons generally have polar orbits, meaning orbits that take them over the north and south poles of the planet they orbit. F) The outer planets are so large that they nearly collide with each other on each orbit.

B) The Sun and most of the planets rotate in the same direction that the planets orbit. C) All the planets orbit the Sun in nearly the same plane. D) Planets have nearly circular orbits. Be sure to note that while the Sun and most planets rotate in the same direction that the planets orbit, there are two notable exceptions: Venus and Uranus. Also note that most major moons orbit in this same direction and in a planet near that of their planet's equator (which means they are not in polar orbits).

The "extraordinary" part of Comte's claim was his statement that we could never learn the composition of stars. Which of the following best summarizes the key lesson we should learn from the fact that his claim was ultimately proven wrong? A) Nothing is impossible. B) The advance of science and technology may someday provide ways to answer questions that seem unanswerable today. C) If a question seems unanswerable, it is only because you are not trying hard enough to find the answer. D) We should not trust the opinions of so-called "experts."

B) The advance of science and technology may someday provide ways to answer questions that seem unanswerable today. The history of science has many other cases in which questions that once seemed unanswerable later became possible to address through science. For example, it once seemed that we could never know the ages of fossils, but the discovery of radioactive decay led to the ability to date rocks and fossils through the method of radiometric dating.

Imagine that we receive a radio message from a civilization living on a planet around another star, and the message tells us that they have seen a television show from Earth that was broadcast in 1962. Which of the following statements can not be true? A) The civilization enjoyed our TV show. B) The civilization is located 100 light-years away. C) The civilization lives on an Earth-like planet. D) The civilization is more technologically advanced than we are. E) The civilization has suffered a major environmental catastrophe since sending the message.

B) The civilization is located 100 light-years away. They have already replied to a broadcast from only about 50 years ago, so they cannot be 100 light-years away because any radio or television message would take 100 years to travel a distance of 100 light-years.

According to the nebular theory of solar system formation, which law best explains why the solar nebula spun faster as it shrank in size? A) The law of universal gravitation B) The law of conservation of angular momentum C) The law of conservation of energy D) Einstein's law E=mc2

B) The law of conservation of angular momentum To conserve angular momentum, the cloud particles had to move faster around the cloud center as their distance from the center decreased.

Consider only the first major feature, which concerns observed patterns of motion in the solar system. Scientifically, which of the following possible conclusions is justified from the patterns of motion alone? View Available Hint(s) A) The planets started out quite small and grew to their current sizes as they gradually accreted more material. B) The planets were not each born in a separate, random event. C) The planets were not born within the past million years, but instead they must have been born billions of years ago. D) The planets were born from a giant cloud of gas that rotated in the same direction that the Milky Way Galaxy rotates.

B) The planets were not each born in a separate, random event. Continue to Part C to explore why this conclusion is justified.

The Milky Way Galaxy is ________. A) a small group of closely spaced stars that we can see in our night sky B) a giant collection of more than 100 billion stars C) our Sun and the planets, moons, and other objects that orbit the Sun D) everything we can in principle observe from Earth

B) a giant collection of more than 100 billion stars Our Sun is one member of this collection, located about halfway out from the center toward the edge of the galactic disk.

O2 is an example of A) both a molecule and a compound B) a molecule only C) a compound only D) a collection of isolated atoms

B) a molecule only

According to current scientific estimates, when did the Big Bang occur? View Available Hint(s) According to current scientific estimates, when did the Big Bang occur? A) about 20 billion years ago B) about 14 billion years ago C) about 10 billion years ago D) about 4 1/2 billion years ago E) about 65 million years ago

B) about 14 billion years ago Scientists estimate the age of the universe by measuring the expansion rate, from which they can determine how long it has taken the universe to reach its current size. Current estimates put this age at about 14 billion years.

The Andromeda Galaxy is faintly visible to the naked eye. When you look at the Andromeda Galaxy, the retina of your eye is absorbing light that has traveled through space for ______ to reach you. A) a few minutes B) about 2 ½ million years C) about 100,000 years D) about 250 years

B) about 2 ½ million years The distance to the Andromeda galaxy is about 2 ½ million light-years, which means light takes about 2 ½ million years to travel from the Andromeda galaxy to us. Therefore, the light that you see from Andromeda travelled through space for 2 ½ million years before being absorbed by your retina.

The fundamental parameters of the universe are so finely tuned that if they had been only slightly different, life would not have been possible. This statement is often referred to as the A) philanthropic principle B) anthropic principle C) mediocrity principle D) cosmological principle

B) anthropic principle

Where would you expect terrestrial planets to form in the solar nebula? View Available Hint(s) A) within the innermost regions (within about the inner 0.3 AU) B) anywhere between the innermost regions (within about the inner 0.3 AU) and the frost line C) anywhere outside the innermost regions (within about the inner 0.3 AU) D) anywhere outside the frost line

B) anywhere between the innermost regions (within about the inner 0.3 AU) and the frost line Terrestrial planets are made mostly of metal and rock and therefore formed in the region in which it was cool enough for metal and rock to condense but still too warm for hydrogen compounds to condense into ices. This means the region between the innermost regions (within about the inner 0.3 AU) and the frost line.

The mysterious component if the universe which appears to be pushing galaxies apart is referred to as A) inflation B) dark energy C) dark matter D) anti-gravity

B) dark energy

The main chemical building blocks of life, carbon, nitrogen, oxygen, and iron were formed A) in the Big Bang that created the universe B) in the nuclear burning cores of stars and then ejected into space when they died C) in the center of the Earth and then ejected onto the surface via volcanism D) inside interstellar gas clouds during star formation

B) in the nuclear burning cores of stars and then ejected into space when they died

Human beings mostly emit which kind of electromagnetic radiation? A) microwave B) infrared C) visible D) ultraviolet

B) infrared

In the illustration of the solar spectrum, the upper left portion of the spectrum shows the __________ visible light. View Available Hint(s) A) lowest speed B) lowest frequency C) highest speed D) brightest E) highest frequency

B) lowest frequency Red light is the longest wavelength visible light, and longer wavelength means lower frequency (because wavelength×frequency=speed of light).

When considering light as made up of individual "pieces," each characterized by a particular amount of energy, the pieces are called ________. A) frequencies B) photons C) wavicles D) gamma rays

B) photons A single photon carries a particular amount of energy, corresponding to a particular frequency and wavelength.

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 __________. A) none of the planets would have ended up with moons B) planetary orbits would have many different orientations and directions, rather than all being in the same direction and in the same plane C) planets would orbit at much higher speeds than they actually do D) there would be many different types of planets, rather than just two major types

B) planetary orbits would have many different orientations and directions, rather than all being in the same direction and in the same plane In science, we form hypotheses to explain something, then use the hypotheses to make predictions that we can test. In this case, we have two alternate hypotheses: random births or birth from a single cloud of gas. The hypothesis of random births predicts random orbits, which does not agree with reality and therefore has been discarded. The hypothesis of birth from a single cloud predicts patterns of motion that match those we observe; this match of prediction and observation provides evidence in favor of the hypothesis.

If you have a telescope that is observing light with wavelengths of a few meters, you are observing __________. A) X rays B) radio waves C) infrared light D) gamma rays E) visible light F) ultraviolet light

B) radio waves As you can see by looking at the wavelength scale that goes with the electromagnetic spectrum, all wavelengths longer than about a millimeter — which therefore includes wavelengths of a few meters — are called radio waves.

X ray photons have a _____ wavelength, _____ frequency, and _____ energy than do ultraviolet photons. A) shorter, lower, higher B) shorter, higher, higher C) longer, lower, higher D) shorter, higher, lower E) longer, lower, lower F) longer, higher, higher

B) shorter, higher, higher X rays have shorter wavelengths than ultraviolet light, and as shown in the video, shorter wavelength means higher frequency and photons with higher energy.

The technique of collecting radiation and splitting it up into its components so it can be analyzed is referred to as A) astrometry B) spectrometry C) colorimetry D) photometry

B) spectrometry

Notice that the Sun's spectrum appears brightest (or most intense) in the yellow-green region. This fact tells us __________. View Available Hint(s) A) that the Sun's surface consists of a layer of cooler gas above a hotter interior B) the approximate temperature of the Sun's surface C) the chemical composition of the Sun D) that the Sun should appear yellow-green to our eyes

B) the approximate temperature of the Sun's surface One of the two laws of thermal radiation (Wien's law) states that the peak wavelength of a spectrum is directly related to an object's temperature. A peak at yellow-green wavelengths corresponds to a temperature of about 5800 K.

If we had detected a signal from an advanced civilization in 2013 which was located at a distance of 7 light-years from the Sun, in what year was the signal actually transmitted? A) 2013 B) 2020 C) 2006 D) 2007

C) 2006

The nearest star is at a distance of 4.2 light-years. Given that light travels at 300,000 km/s in space, how far away is the nearest star in kilometers (km)? A) 2.7 x10^15 km B) 3.0 x10^8 km C) 4.0 x10^13 km D) 9.5 x10^12 km

C) 4.0 x10^13 km

We expect a scientific theory to be able to make predictions that can be tested. Which of the following is a prediction of the nebular theory that has been verified by observations? A) Large planets should have at least some moons that are larger than the smallest planets. B) Earth-size planets should have fairly large moons. C) Many stars should have planets. D) Planetary orbits should lie in approximately the same plane as the disk of the Milky Way Galaxy.

C) Many stars should have planets. The nebular theory explains planetary formation as a natural part of the star formation process, and therefore predicts that planets should be fairly common around other stars. This prediction was made long before we ever discovered such planets, so the fact that planets are indeed common is a tremendous predictive success for the nebular theory.

Due to the incredible size of the universe, our search for extraterrestrial life will probably be limited to within our A) solar system B) Local Supercluster of galaxies C) Milky Way galaxy D) Local Group of galaxies

C) Milky Way galaxy

Which of the following statements best describes what astronomers mean when they say that the universe is expanding? View Available Hint(s) A) The observable universe is growing larger in radius at a rate of one light-year per year. B) The average distance between stars in the Milky Way Galaxy is increasing with time. C) The average distance between galaxies is increasing with time. D) The universe itself is not growing, but our knowledge of the universe is increasing with time. E) All objects in the universe, including Earth and everything on it, are gradually growing in size.

C) The average distance between galaxies is increasing with time. Keep in mind that while the universe as a whole is expanding, individual galaxies (and gravitationally bound groups or clusters of galaxies) and their contents do not expand. That is why the average distances between galaxies grow with time, but objects such as people, Earth, the solar system, and the Milky Way Galaxy remain stable in size.

Which one of the following is not one of the four major features of the solar system? A) exceptions to the general trends stand out. B) Swarms of asteroids and comets populate the solar system. C) The solar system contains eight planets plus dwarf planets (such as Ceres, Pluto, and Eris). D) Planets fall into two major categories (terrestrial and jovian). E) Large bodies in the solar system have orderly motions.

C) The solar system contains eight planets plus dwarf planets (such as Ceres, Pluto, and Eris). The precise number of planets is not thought to be of any particular significance, and the division between "planets" and "dwarf planets" is a recent classification scheme that does not affect the basic ideas in the four major features. That is, for the purposes of the four major features, the dwarf planets are considered to be equivalent to large asteroids or comets.

Part F Part complete Today, the evidence that we live in an expanding universe is extremely strong because astronomers have measured the motions of millions of galaxies. Nevertheless, in science, we must always remain open to the possibility that some future observation could call even our most strongly supported theories into question. Which of the following hypothetical observations would not be consistent with what we expect in an expanding universe? View Available Hint(s) A) You discover a pair of distant galaxies that are colliding with one another. B) You discover an extremely distant galaxy that is moving away from us at 90% of the speed of light. C) You discover an extremely distant galaxy that is moving toward us.

C) You discover an extremely distant galaxy that is moving toward us. In an expanding universe, extremely distant galaxies must be moving away from us, just as distant raisins in the raisin cake must be moving away. It would make no sense to find an extremely distant galaxy that was moving toward us, and such an observation would, therefore, cause us to question the very idea of an expanding universe. Provide Feedback

On the cosmic calendar, which compresses the history of the universe into a single year, about when did life arise on Earth? View Available Hint(s) On the cosmic calendar, which compresses the history of the universe into a single year, about when did life arise on Earth? A) in late January B) in mid-August C) in September D) in mid-December E) just a few hours before midnight on December 31

C) in September From Part C, Earth formed in early September on the cosmic calendar. Life apparently arose on Earth within less than a billion years after that, which means it was still in September (because each month on the cosmic calendar represents about 1.2 billion years).

In essence, the nebular theory holds that _________. A) nebulae are clouds of gas and dust in space B) the planets each formed from the collapse of its own separate nebula C) our solar system formed from the collapse of an interstellar cloud of gas and dust D) the planets formed as a result of a near collision between our Sun and another star

C) our solar system formed from the collapse of an interstellar cloud of gas and dust This cloud of gas and dust that gave birth to our solar system is called the solar nebula.

The jovian planets are thought to have formed as gravity drew hydrogen and helium gas around planetesimals made of __________. A) only rocks and metals B) only ices C) rocks, metals, and ices D) rocks, metals, ices, and hydrogen and helium gases

C) rocks, metals, and ices Because ices could condense only beyond the frost line, we expect jovian planets to form only beyond the frost line. Note that many extrasolar planets appear to be jovian but are located close to their stars, leading scientists to suspect that these planets migrated inward after originally forming beyond the frost lines of their star systems. Provide Feedback

Based on what you've learned from the raisin cake analogy, which two properties of distant galaxies do astronomers have to measure to show that we live in an expanding universe? View Available Hint(s) A) their ages and masses B) their distances and masses C) their distances and speeds D) their ages and distances

C) their distances and speeds The analogy shows that if you lived in an expanding raisin cake, you would see all other raisins moving away from yours, with more distant ones moving faster. This is exactly what we observe for galaxies outside our Local Group, which is why we conclude that we live in an expanding universe.

Suppose we obtain a single, detailed (high-resolution) spectrum of a star located many light-years away. What can we learn about the star? Sort each of the following characteristics of a star into the correct bin based on whether we can or cannot learn it from the single spectrum. A) surface temperature B) speed toward or away from us C) chemical composition (surface) D) interior temperature E) size (diameter) F) distance G) mass H) speed across our line of sight

Can learn from single spectrum A) surface temperature B) speed toward or away from us C) chemical composition (surface) Cannot learn from single spectrum D) interior temperature E) size (diameter) F) distance G) mass H) speed across our line of sight Note that while we can learn only three of the above eight characteristics from a single spectrum, we can learn all of the others through other types of observations that you will learn about in later chapters of your textbook.

The fact that the elements of life were produced in stars suggests the following two things: A) (1) The universe began in a Big Bang. (2) The elements of life exist in all stars. B) (1) These elements only exist in very old stars. (2) These elements are extremely rare. C) (1) These elements have become more common as the universe has grown older. (2) These elements are the most common elements in the universe. D) (1) These elements have become more common as the universe has grown older. (2) These elements should be found in nearly all star systems.

D) (1) These elements have become more common as the universe has grown older. (2) These elements should be found in nearly all star systems. These ideas provide at least some reason to think that life could be widespread

Which of the following best describes the structure of an atom? A) A relatively large nucleus made of protons and neutrons, with electrons found inside the protons and neutrons B) Electrons orbit the atom's nucleus in exactly the same way that planets orbit the Sun C) A tiny collection of protons, neutrons, and electrons, all mixed together randomly D) A tiny nucleus, made of protons and neutrons, surrounded by a "cloud" of electrons that give the atom its physical size

D) A tiny nucleus, made of protons and neutrons, surrounded by a "cloud" of electrons that give the atom its physical size Most of the mass therefore resides in the tiny nucleus, though most of the volume comes from the cloud of electrons.

Suppose we want to know what the Sun is made of. What should we do? View Available Hint(s) A) Find the precise wavelength at which the background rainbow of color peaks in brightness. B) Count the total number of black lines in the Sun's spectrum. C) Precisely measure the intensity of light in each of the black lines in the spectrum. D) Compare the wavelengths of lines in the Sun's spectrum to the wavelengths of lines produced by chemical elements in the laboratory.

D) Compare the wavelengths of lines in the Sun's spectrum to the wavelengths of lines produced by chemical elements in the laboratory. Each chemical element (or ion or molecule) produces a unique set of spectral lines; the wavelengths of these lines can be measured in the laboratory. If the Sun's spectrum contains the set of lines for some particular element, we conclude that the Sun contains that element. We determine the Sun's overall chemical composition by examining all the lines in its spectrum.

Which of the following statements about nuclear fusion is not true? A) It is the process that has made most of the elements of which we and the Earth are made. B) It is the process that generates the energy by which our Sun shines. C) It involves two or more small atomic nuclei slamming into each other and sticking together to make a larger atomic nucleus. D) It refers solely to the process of converting hydrogen into helium.

D) It refers solely to the process of converting hydrogen into helium. Converting hydrogen into helium is just one of many different fusion reactions that occur in stars.

Suppose you know the frequency of a photon and the speed of light. What else can you determine about the photon? A) Its acceleration B) Its temperature C) The chemical composition of the object that emitted it D) Its wavelength and energy

D) Its wavelength and energy Once you know frequency, you can calculate both wavelength and energy.

Which of the following procedures would allow you to make a spectrum of the Sun similar to the one shown, though with less detail? View Available Hint(s) A) Take a photograph of the Sun and then use image-processing software to change the Sun's shape into a long, thin strip. B) Photograph the Sun through a powerful telescope. C) Compare the relative amounts of light that the Sun emits as infrared, visible light, and ultraviolet light. D) Pass a narrow beam of sunlight through a prism.

D) Pass a narrow beam of sunlight through a prism. The prism bends different wavelengths of light by different amounts, causing the white light from the Sun to spread out into a rainbow of colors. Absorption features appear as dark lines against the brighter background of the spectrum.

Which of the following is not a general difference between a planet and a star? A) Planets orbit stars, and stars orbit the center of the galaxy. B) Planets are smaller than stars. C) Planets are dimmer than stars. D) Planets are made of rock and stars are made of gas.

D) Planets are made of rock and stars are made of gas. Planets are not necessarily made of rock; they may be rocky, icy, or gaseous in composition.

Note that an observer located at the Local Raisin would see Raisins 1, 2, and 3 all move away from her during the video. What would an observer located at Raisin 2 see? View Available Hint(s) A) Raisin 1 and Raisin 3 both move toward her. B) Raisin 1 moves away from her while Raisin 3 moves toward her. C) Raisin 1 moves toward her while Raisin 3 moves away from her. D) Raisin 1 and Raisin 3 both move away from her.

D) Raisin 1 and Raisin 3 both move away from her. In fact, observers at any raisin would see all the other raisins moving away. Note also that the farther away a raisin is located from the observer, the faster it moves away — which is just what Hubble discovered for galaxies in the universe.

Which of the following best describes why the Sun's spectrum contains black lines over an underlying rainbow? View Available Hint(s) A) The Sun produces a continuous rainbow of color, while the black lines are caused by imperfections in the instruments used to record the spectrum. B) The rainbow colors represent emission by particular chemical elements, while the black lines represent gaps where no element can emit light. C) The Sun produces a continuous rainbow of color, while the black lines are caused by atoms and molecules in Earth's atmosphere. D) The Sun's hot interior produces a continuous rainbow of color, but cooler gas at the surface absorbs light at particular wavelengths.

D) The Sun's hot interior produces a continuous rainbow of color, but cooler gas at the surface absorbs light at particular wavelengths. The Sun's spectrum is an absorption line spectrum, which is produced when continuous light from a hot source (the Sun's interior) passes through a cooler cloud of gas (the gas that makes up the Sun's visible surface).

Which of the following best describes why we think the terrestrial planets formed in the inner solar system and the jovian planets formed in the outer solar system? A) The large jovian planets occupy much more space than the small terrestrial planets, so they can exist only in places like the outer solar system, where there is a lot more space available than in the inner solar system. B) The terrestrial planets grew from "seeds" of metal and rock, and these materials could condense only in the inner solar system. C) The jovian planets were made largely from gas, and nearly all the gas from which our solar system formed was in the outer solar system. D) The terrestrial planets grew from "seeds" of metal and rock, whereas the jovian planets grew from seeds that also contained hydrogen compounds that condensed only in the cold outer solar system.

D) The terrestrial planets grew from "seeds" of metal and rock, whereas the jovian planets grew from seeds that also contained hydrogen compounds that condensed only in the cold outer solar system. For this reason, we expect that jovian planets must always form in the outer regions of solar systems, where it is cold enough for hydrogen compounds to condense into ices.

Suppose you want to know the chemical composition of a distant star. Which piece of information is most useful to you? A) The peak energy of the star's thermal radiation B) The Doppler shift of the star's spectrum C) Whether the star's spectrum has more emission lines or more absorption lines D) The wavelengths of spectral lines in the star's spectrum

D) The wavelengths of spectral lines in the star's spectrum Different chemical elements and ions produce different sets of spectral lines.

Planetary rings are found around A) all of the planets B) the planet Saturn only C) all of the terrestrial planets D) all of the Jovian planets

D) all of the Jovian planets

Each choice describes two atoms, but the two atoms are isotopes of one another in only one case. Which one? A) carbon-12 with six electrons and oxygen-16 with eight electrons B) carbon-12 with six electrons and carbon-12 with five electrons C) carbon-12 with six electrons and oxygen-16 with six electrons D) carbon-12 and carbon-14 E) carbon-12 and oxygen-16

D) carbon-12 and carbon-14 Isotopes are atoms of the same element with different numbers of neutrons and hence different atomic mass numbers.

Most of the mass of the universe is in the form of A) gas clouds B) stars C) black holes D) dark matter

D) dark matter

Telescopic observations of distant galaxies have shown that the universe is A) infinite in size B) contracting C) static and unchanging D) expanding

D) expanding

The most abundant materials in the solar nebula were A) hydrogen compounds like water, methane, and ammonia B) rocks C) metals D) hydrogen and helium gases

D) hydrogen and helium gases

On the cosmic calendar, which compresses the history of the universe into a single year, about when did Earth form? View Available Hint(s) On the cosmic calendar, which compresses the history of the universe into a single year, about when did Earth form? A) very early in January B) in mid-February C) in June D) in early September E) in mid-December

D) in early September The cosmic calendar compresses the 14-billion-year history of the universe into 1 year, which means that each month represents about 1.2 billion years. The solar system's age of 4 ½ billion years therefore puts its birth in early September.

Red light has a _____ wavelength and a _____ frequency than does blue light. A) shorter, higher B) shorter, lower C) longer, higher D) longer, lower

D) longer, lower Red light has a wavelength of about 700 nm, which is longer than the 400-nm wavelength of blue light. As explained in the video, longer wavelength means lower frequency for light.

Suppose that you had "X-ray vision" that allowed you to see X rays. What would you notice when you looked at a friend standing near you that you could not notice with your visible light vision alone? A) you could see color of your friend's underwear B) you could see your friend's internal bone structure C) you could see your friend's internal muscles but not bones D) nothing

D) nothing As shown in the figure and video, people emit infrared light but we do not emit X-rays — which is a good thing, because X rays can be harmful. So X-ray vision would be useless when looking at other people, since there would be nothing to see.

In the context of studying major bodies of our solar system, what category of object does our Moon best fit? A) jovian planet B) large comet C) jovian moon D) terrestrial world E) small asteroid

D) terrestrial world We consider the Moon to be one of the terrestrial worlds because of its similarity in size, mass, and composition to the other terrestrial worlds (Mercury, Venus, Earth, and Mars). As you will see when we study comparative planetology, this categorization is useful for understanding geological processes on the terrestrial worlds.

Which of the following words best describes the sum total of all matter and energy that exists? A) multiverse B) supercluster C) macrocosm D) universe

D) universe

The distance between adjacent peaks of an electromagnetic wave is referred to as its A) energy B) frequency C) speed D) wavelength

D) wavelength

Which of the following is not a general distinction between terrestrial planets and jovian planets? A) Terrestrial planets formed much closer to the Sun than did the jovian planets. B) Jovian planets are much more massive than terrestrial planets. C) Terrestrial planets are made largely of metal and rock, whereas jovian planets are made largely of hydrogen and helium. D) Jovian planets tend to have many more moons than terrestrial planets. E) Terrestrial planets have oceans of liquid water and jovian planets do not.

E) Terrestrial planets have oceans of liquid water and jovian planets do not. Mercury, Venus, Earth, and Mars are all terrestrial planets, but only Earth has oceans.

On the cosmic calendar, which compresses the history of the universe into a single year, about when did early humans first walk on Earth? View Available Hint(s) On the cosmic calendar, which compresses the history of the universe into a single year, about when did early humans first walk on Earth? A) in June B) in September C) in mid-December D) on December 30 E) just a few hours before midnight on December 31

E) just a few hours before midnight on December 31 The cosmic calendar compresses the 14-billion-year history of the universe into 1 year, which means that each day represents about 1/365 of 14 billion years, or about 40 million years. Early humans arose just a few million years ago, which therefore means just a few hours before the present moment (the stroke of midnight on December 31) on the cosmic calendar.

What substances were found in the innermost regions (within about the inner 0.3 AU) of the solar system before planets began to form? A) nothing at all B) only rocks and metals C) only hydrogen compounds D) only hydrogen and helium gases E) rocks, metals, hydrogen compounds, hydrogen, and helium, all in gaseous form

E) rocks, metals, hydrogen compounds, hydrogen, and helium, all in gaseous form As described in the video and your textbook, all the materials of the solar nebula were present in the inner region, but it was too hot for any of them to condense. As a result, they were all in gaseous form.

Listed following are characteristics that can identify a planet as either terrestrial or jovian. Match these to the appropriate category. Consider only the planets of our own solar system. A) small size B) solid, rocky surface C) located within the inner solar system D) low average density E) extensive ring systems F) primarily composed of hydrogen, helium, and hydrogen compounds G) numerous orbiting moons

Terrestrial planets A) small size B) solid, rocky surface C) located within the inner solar system Jovian planets D) low average density E) extensive ring systems F) primarily composed of hydrogen, helium, and hydrogen compounds G) numerous orbiting moons