Astronomy Test 2 Review
The temperature of the corona's gas is some 1 to 2 million Kelvin.
All of the following statements about the Sun's corona are true. Which one explains why it is a source of X rays?
clockwise
As seen far above the Earth's south pole, the planets will orbit in a ____________ direction.
Its surface is cooler than the surface of the Sun.
Betelgeuse is the bright red star representing the left shoulder of the constellation Orion. All the following statements about Betelgeuse are true. Which one can you infer from its red color?
Charge = +2; number of remaining electrons = 6
Consider an atom of oxygen in which the nucleus contains eight protons and eight neutrons. If it is doubly ionized, what is the charge of the oxygen ion and how many electrons remain in the ion?
plate tectonics
Continental drift, earthquakes, faults, and volcanic activity are the result of a process known as _______________
Atom 1: nucleus with seven protons and eight neutrons, surrounded by seven electrons; Atom 2: nucleus with seven protons and seven neutrons, surrounded by seven electrons
Each of the following describes an "Atom 1" and an "Atom 2." In which case are the two atoms different isotopes of the same element?
D
Earth's stratosphere is heated primarily by which process? A. Greenhouse gases absorb infrared radiation. B. Greenhouse gases are broken apart by X rays. C. Atoms and molecules absorb infrared sunlight. D. Ozone is broken apart by ultraviolet radiation. E. Ozone absorbs visible sunlight.
wavelength
Gamma rays have a small ______.
D
How did the lunar maria form? A. The giant impact that created the Moon left smooth areas that we call the maria. B. The maria are the result of gradual erosion by micrometeorites striking the Moon. C. Volatiles escaping from the Moon's interior heated and eroded the surface in the regions of the maria. D. Large impacts fractured the Moon's lithosphere, allowing lava to fill the impact basins. E. The early bombardment created heat that melted the lunar surface in the regions of the maria.
27.3
How long does (number of days to nearest tenth) it take the Moon to rotate once about its axis?
B
Hydrogen fusion in the Sun requires a temperature (in Kelvin) of A. any temperature, as long as gravity is strong enough. B. millions of degrees. C. trillions of degrees. D. thousands of degrees. E. billions of degrees.
16 times
If one quadruples the size of the collecting element of an optical telescope, how much more light is collected?
The planet is rotating.
If we observe one edge of a planet to be redshifted and the opposite edge to be blueshifted, what can we conclude about the planet?
The star is moving toward us.
Laboratory measurements show hydrogen produces a spectral line at a wavelength of 486.1 nanometers (nm). A particular star's spectrum shows the same hydrogen line at a wavelength of 486.0 nm. What can we conclude?
a hot, thin (low-density, nearly transparent) gas
No object produces a perfect thermal radiation spectrum, but many objects produce close approximations. Which of the following would not produce a close approximation to a thermal radiation spectrum?
11
On average, the sunspot cycle occurs every __________ years.
ultraviolet
Ozone is a good absorber of what form of radiation?
The total amount of light in the spectrum tells us the star's radius.
Studying a spectrum from a star can tell us a lot. All of the following statements are true except one. Which statement is not true?
cooler
Sunspots apppear dark due to the fact they are _____ than their surroundings.
E
Sunspots are cooler than the surrounding solar surface because A. they are regions where convection carries cooler material downward. B. there is less fusion occurring there. C. magnetic fields lift material from the surface of the Sun, cooling off the material faster. D. magnetic fields trap ionized gases that absorb light. E. strong magnetic fields slow convection and prevent hot plasma from entering the region.
1 meter
Suppose a photon has a frequency of 300 million hertz (300 megahertz). What is its wavelength?
Star X is moving away from us faster than Star Y.
Suppose that Star X and Star Y both have redshifts, but Star X has a larger redshift than Star Y. What can you conclude?
The faster rotating star has wider spectral lines than the slower rotating star.
Suppose that two stars are identical in every way; for example, same distance, same mass, same temperature, same chemical composition, and same speed relative to Earth, except that one star rotates faster than the other. Spectroscopically, how could you tell the stars apart?
D
Suppose that, for some unknown reason, the core of the Sun suddenly became hotter. Which of the following best describes what would happen? A. Nothing would happen; things would remain the same. B. Higher temperature would cause the rate of nuclear fusion to rise, which would increase the internal pressure, causing the core to expand and turn the Sun into a giant star. C. The higher temperature would not affect the fusion rate but would cause the core to expand and cool until the temperature returned to normal, with the core at a new, slightly larger size. D. Higher temperature would cause the rate of nuclear fusion to rise, which would increase the internal pressure, causing the core to expand and cool until the fusion rate returned to normal. E. Higher temperature would cause the rate of fusion to fall, decreasing the internal pressure and causing the core to collapse until the rate of fusion returned to normal.
The radio waves from the radio station are causing electrons in your radio's antenna to move up and down 97 million times each second.
Suppose you are listening to a radio station that broadcasts at a frequency of 97 Mhz (megahertz). Which of the following statements is true?
It would vaporize (evaporate) into a gas, then the molecules would dissociate into individual oxygen atoms, then the atoms would become increasingly ionized as you continued to raise the temperature.
Suppose you had molecular oxygen (O2) chilled enough so that it was in liquid form. Which of the following best describes the phase changes that would occur as you heated the liquid oxygen to high temperature?
6000 joules
Suppose you have a 100-watt light bulb that you leave turned on for one minute. How much energy does it use?
High spectral resolution.
Suppose you want to determine the chemical composition of a distant planet or star. Which of the following will be most useful to have?
proton proton chain
The Sun produces its energy by means of a fusion reaction called __________ (no abbreviation) reaction.
convection zone
The _____ is the solar layer in which energy is transported outward by convection, which means hot material will rise and cooler material will fall.
corona
The _____ is the tenuous uppermost layer of the Sun's atmosphere where most of the Sun's X rays are emitted and the temperature is about 1 million K.
focal plane
The ________ of a telescope is the place where, if we mounted film or an electronic detector, we could get a clear (not blurry) image of an object viewed through the telescope.
corona
The __________ is the tenuous uppermost layer of the Sun's atmosphere where most of the Sun's X rays are emitted and the temperature is about 1 million K.
Mars & Jupiter
The asteroid belt is located between the orbits of the 2 planets _____ & _____?
E
The core, mantle, and crust of a planet are defined by differences in their A. geological activity. B. strength. C. all of the above. D. temperature. E. composition.
chromatic aberration
The dispersion of white light by lenses causes an optical defect called ________ in refractors.
The two spectra would have similar shapes, except Neptune's spectrum would be missing a big chunk of the red light that is present in the Sun's spectrum.
The planet Neptune is blue in color. How would you expect the spectrum of visible light from Neptune to be different from the visible-light spectrum of the Sun?
F
True or False: A radio telescope and an optical telescope of the same size have the same angular resolution.
T
True or False: Although the Sun does not generate energy by gravitational contraction today, this energy-generation mechanism was important when the Sun was forming.
F
True or False: Gravitational equilibrium means that the surface and the core of the Sun are at the same pressure.
T
True or False: Gravitational equilibrium means that the surface and the core of the Sun are at the same pressure.
F
True or False: The Sun generates energy primarily by nuclear fission.
T
True or False: The angular resolution of a telescope is never less than its diffraction limit.
E
What are coronal holes? A. regions on the photosphere where magnetic lines poke through, creating the cooler areas of the sunspots B. all of the above C. tunnels in the outer layers of the Sun through which photons can escape more quickly than through the radiation zone D. holes in the corona of the Sun that allow us to see the photosphere E. areas of the corona where magnetic field lines project into space, allowing charged particles to escape the Sun, becoming the solar wind
A
What are greenhouse gases? A. gases that absorb infrared light B. gases that transmit visible light C. gases that transmit infrared light D. gases that absorb visible light E. gases that absorb ultraviolet light
D
What causes stars to twinkle? A. the inability of the human eye to see faint objects B. variable absorption by interstellar gas along the line of sight to the star C. It is intrinsic to the stars and their brightness varies as they expand and contract. D. bending of light rays by turbulent layers in the atmosphere E. variations in the absorption of the atmosphere
Light pollution is light from human sources that makes it difficult to see the stars at night.
What do astronomers mean by light pollution?
It is the angular resolution the telescope could achieve if nothing besides the size of its light-collecting area affected the quality of its images.
What do we mean by the diffraction limit of a telescope?
B
What do we mean by the diffraction limit of a telescope? A. It is the maximum size to which any telescope can be built. B. It is the best angular resolution the telescope could achieve with perfect optical quality and in the absence of atmospheric distortion. C. It describes the maximum exposure time for images captured with the telescope. D. None of the other choices. E. It describes the farthest distance to which the telescope can see.
The angular size of the smallest features that the telescope can see
What does angular resolution measure?
C
What does angular resolution measure? A. The number of electromagnetic waves captured by an image. B. The brightness of an image. C. The angular size of the smallest imaged features. D. The angular height of an image. E. The angular width of an image.
A
What is granulation in the Sun? A. the bubbling pattern on the photosphere produced by the underlying convection B. lumps of denser material in the Sun C. another name for the way sunspots look on the surface of the Sun D. elements in the Sun other than hydrogen and helium E. dust particles in the Sun that haven't been turned into plasma
C
What is the Kuiper belt? A. The most prominent ring of Saturn that is visible in photographs. B. A technical name for the asteroid belt. C. A region of the solar system beginning just beyond the orbit of Neptune that contains many icy comets. D. A region of the solar system that extends almost a fourth of the way to the nearest stars and contains a trillion comets with orbits going in all directions around the Sun. E. A region of the solar system beginning just beyond the orbit of Pluto that contains many icy comets.
about 1 arcminute, or 1/60 of a degree
What is the angular resolution of the human eye?
5800 K
What is the effective temperature of the photosphere to two significant figures?
It reduces blurring caused by atmospheric turbulence for telescopes on the ground.
What is the purpose of adaptive optics?
It allows two or more small telescopes to achieve the angular resolution of a much larger telescope.
What is the purpose of interferometry?
B
What kind of surface features may result from tectonics? A. volcanos B. all of the other 4 choices C. valleys D. cliffs E. mountains
granulation
What solar phenomenon that takes place on the Sun's surface gives direct evidence of the convective motion of gases below the surface?
A
What two forces are balanced in what we call gravitational equilibrium? A. outward pressure and gravity B. the strong force and kinetic energy C. outward pressure and the strong force D. the strong force and gravity E. the electromagnetic force and gravity
In your eye, the image forms on your retina, much as the image forms on the detector in a camera.
When your eye forms an image, the _____ plays a role analogous to the detector in a camera.
thermosphere or ionosphere
Which layer of the Earth's atmosphere is responsible for the possibility of radio communications?
D
Which layer of the Sun do we normally see? A. chromosphere B. convection zone C. radiation zone D. photosphere E. corona
E
Which of the following best describes convection? A. It is the process in which warm material gets even warmer and cool material gets even cooler. B. It is the process by which rocks sink in water. C. It is the process in which a liquid separates according to density, such as oil and water separating in a jar. D. It is the process in which bubbles of gas move upward through a liquid. E. It is the process in which warm material expands and rises while cool material contracts and falls.
It is the place where, if we mounted film or an electronic detector, we could get a clear (not blurry) image of an object viewed through the telescope.
Which of the following best describes what we mean by the focal plane of a telescope?
A
Which of the following best describes why radio telescopes are generally much larger in size than telescopes designed to collect visible light? A. Getting an image of the same angular resolution requires a much larger telescope for radio waves than for visible light. B. Since radio waves possess long wavelengths, it is necessary to build large telescopes to detect them. C. Objects that emit radio waves are always much larger than objects that emit visible light, and therefore require larger telescopes. D. Radio telescopes are designed to collect sound rather than light. E. It is because radio telescopes are used in the daytime and visible light telescopes are used at night.
The passage of a light wave can cause electrically charged particles to move up and down. That is, electrically charged particles can respond to (or generate) electromagnetic radiation.
Which of the following best describes why we say that light is an electromagnetic wave?
The cloud is cool and lies between you and a hot star.
Which of the following conditions lead you to see an absorption line spectrum from a cloud of gas in interstellar space?
A
Which of the following describes tectonics? A. the disruption of a planet's surface by internal stresses B. the eruption of molten rock from a planet's interior to its surface C. the excavation of bowl-shaped depressions by asteroids or comets striking a planet's surface D. the wearing down or building up of geological features by wind, water, ice, and other phenomena of planetary weather E. none of the above
twinkling of stars
Which of the following effects is caused by atmospheric turbulence?
They are always shown with colors that are not the true colors of the objects that were photographed.
Which of the following is always true about images captured with X-ray telescopes?
C
Which of the following is not evidence for continental drift on Earth? A. earthquakes B. high ocean ridges between the continents C. the paucity of impact craters D. similar rocks and fossils are found in different continents E. some continental boundaries fit together like pieces of a jigsaw puzzle
Filtering to look at just a single color from an object.
Which of the following is not one of the three main categories of observation generally used by astronomers?
X rays travel through space faster than radio waves.
Which of the following statements about X rays and radio waves is not true?
Electrons orbit the nucleus rather like planets orbiting the Sun.
Which of the following statements about electrons is not true?
B
Which of the following statements about light focusing is not true? A. All of the above statements are true. B. The focal plane of a reflecting telescope is always located within a few inches of the primary mirror. C. Film should be placed at the focal plane in a camera. D. In a healthy eye, light is focused on the retina. E. If you try to look at an image that is not formed at the focal plane, it will be blurry.
E
Which of the following statements about the greenhouse effect is true? A. Without the naturally occurring greenhouse effect, the earth would be too cold to have liquid oceans. B. The burning of fossil fuels increases the greenhouse effect on Earth because of the release of carbon dioxide. C. One result of an increased greenhouse effect on Earth may be an increased number of severe storms. D. A weak greenhouse effect operates on Mars. Correct E. All of the other 4 statements are true.
A hot object emits more radiation per unit surface area than a cool object.
Which of the following statements about thermal radiation is always true?
A refracting telescope uses a transparent glass lens to focus light, whereas a reflecting telescope uses a mirror to focus light.
Which of the following statements best describes the difference between a refracting telescope and a reflecting telescope?
Telescopes can collect far more light with far better angular resolution.
Which of the following statements best describes the two principle advantages of telescopes over eyes?
It absorbs red light and reflects green light.
Which of the following statements is true of green grass?
radio, visible, and very limited portions of the infrared and ultraviolet regions
Which of the following wavelength regions can be studied with telescopes on the ground?
Impact or Giant Impact
Which origin model of the Moon do astronomers prefer?
E
Which planet has a ring system? A. Jupiter B. Uranus C. Saturn D. Neptune E. all 4 planets possess a ring system
E
Which statement best describes the solar neutrino problem? A. Our current understanding of fusion in the Sun suggests that all neutrinos should be destroyed before they arrive at the earth, yet neutrinos are being detected. B. The term solar neutrino problem refers to the fact that neutrinos are extremely difficult to detect. C. No one understands how it can be possible for neutrinos to be produced in the Sun. D. Theoretical models predict that neutrinos should be produced in the Sun, but no neutrinos have ever been observed to be coming from the Sun. E. Solar neutrinos have been detected, but in fewer numbers than predicted by theoretical models.
B
Why does the Moon have a layer of powdery "soil" (regolith) on its surface? A. The soil exists because the Moon accreted from powdery material after a giant impact blasted the earth. B. It's the result of gradual erosion by micrometeorites striking the Moon. C. Volatiles escaping from the Moon's interior bubble upward and make the soil. D. Large impacts shattered lunar rock to make this soil. E. The soil is the result of the same processes that make powdery sand on Earth.
Perigee
______________ is the point in the Moon's orbit that is closest to the Earth.
