ASTR 1404 Exam 2 Review

The light-gathering power of a 4-meter telescope is __________ than that of a 2-meter telescope. a. 4 times larger b. 8 times larger c. 2 times smaller d. 16 times smaller

a. 4 times larger

Why is an iron atom a different element from a sodium atom? a. An iron atom has more protons in its nucleus than a sodium atom has. b. A sodium atom has fewer neutrons in its nucleus than an iron atom has. c. A sodium atom has more electrons. d. A sodium atom is bigger than an iron atom.

a. An iron atom has more protons in its nucleus than a sodium atom has.

If the Sun instantaneously stopped giving off light, what would happen on Earth? a. Earth would get dark 8 minutes later. b. Earth would get dark 1 hour later. c. Earth would get dark 27 minutes later. d. Earth would immediately get dark.

a. Earth would get dark 8 minutes later.

If the radius of an object's orbit is halved, and angular momentum is conserved, what must happen to the object's speed? a. It must be doubled. b. It must stay the same. c. It must be halved. d.It must be squared.

a. It must be doubled.

Star A and star B appear equally bright in the sky. Star A is twice as far away from Earth as star B. How do the luminosities of stars A and B compare? a. Star A is 4 times as luminous as star B. b. Star B is 4 times as luminous as star A. c. Star B is 2 times as luminous as star A. d. Star A is 2 times as luminous as star B.

a. Star A is 4 times as luminous as star B.

Suppose an abnormally large amount of hydrogen suddenly burned in the core of the Sun. Which of the following would be observed first? a. The Sun would emit more neutrinos. b. The Sun would become brighter. c. The Sun would become bluer. d. The Sun would swell and become larger.

a. The Sun would emit more neutrinos.

Cameras that use adaptive optics provide higher-spatial-resolution images primarily because a. deformable mirrors are used to correct the blurring due to Earth's atmosphere. b. they simulate a much larger telescope. c. they operate above Earth's atmosphere. d. composite lenses correct for chromatic aberration.

a. deformable mirrors are used to correct the blurring due to Earth's atmosphere.

Arrays of radio telescopes can produce much better resolution than single-dish telescopes because they work based on the principle of a. interference. b. refraction. c. diffraction. d. reflection.

a. interference.

The spectroscopic radial velocity method preferentially detects a. large planets close to the central star. b. small planets close to the central star. c. large planets far from the central star. d. small planets far from the central star. e. the method detects all of these equally well.

a. large planets close to the central star.

The transit method preferentially detects a. large planets close to the central star. b. small planets close to the central star. c. large planets far from the central star. d. small planets far from the central star. e. the method detects all of these equally well

a. large planets close to the central star.

Sunspots, flares, prominences, and coronal mass ejections are all caused by a. magnetic activity on the Sun. b. the interaction of the Sun's magnetic field and the interstellar medium. c. the interaction of the solar wind and the Sun's magnetic field. d. electrical activity on the Sun. e. the interaction of the solar wind and Earth's magnetic field.

a. magnetic activity on the Sun.

The part of the human eye that acts as the detector is the a. retina. b. iris. c. pupil. d. lens.

a. retina.

Because angular momentum is conserved, an ice-skater who throws her arms out will a. rotate more slowly. b. rotate at the same rate. c. rotate more quickly. d. stop rotating entirely.

a. rotate more slowly.

When a boat moves through the water, the waves in front of the boat bunch up, while the waves behind the boat spread out. This is an example of a. the Doppler effect. b. the Bohr model. c. emission and absorption. d. the wave nature of light.

a. the Doppler effect.

If a planet is in thermal equilibrium, a. the amount of energy leaving equals the amount of energy arriving. b. the temperature is very low. c. no energy is leaving the planet. d. no energy is arriving on the planet.

a. the amount of energy leaving equals the amount of energy arriving.

Unlike the giant planets, the terrestrial planets formed when a. the inner Solar System was hotter than the outer Solar System. b. the inner Solar System was moving faster than the outer Solar System. c. the outer Solar System took up more volume than the inner Solar System, so there was more material to form planets. d. the inner Solar System was richer in heavy elements than the outer Solar System.

a. the inner Solar System was hotter than the outer Solar System.

The planets in the inner part of the Solar System are made primarily of refractory materials; the planets in the outer Solar System are made primarily of volatiles. The difference occurred because a. there were no volatiles in the inner part of the accretion disk. b. the volatiles on the inner planets were lost soon after the planet formed. c. the outer Solar System has gained more volatiles from space since formation. d. refractory materials are heavier than volatiles, so they sank farther into the nebula.

a. there were no volatiles in the inner part of the accretion disk.

What is the surface temperature of a star that has a peak wavelength of 290 nm? a. 1000 K b. 10,000 K c. 5000 K d. 2000 K e. 100,000 K

b. 10,000 K

If the radius of a spherical object is halved, what must happen to the period so that the spin angular momentum is conserved? a. It must be multiplied by 4. b. It must be divided by 4. c. It must be halved. d. It must stay the same. e. It must double.

b. It must be divided by 4.

Coronal mass ejections a. carry away 1 percent of the mass of the Sun each year. b. are caused by breaking magnetic fields. c. are unimportant to life on Earth. d. are always emitted in the direction of Earth.

b. are caused by breaking magnetic fields.

The temperature of an object has a very specific meaning as it relates to the object's atoms. A high temperature means that the atoms a. are very large. b. are moving very fast. c. are all moving together. d.have a lot of energy.

b. are moving very fast.

The angular resolution of a ground-based telescope is usually determined by a. diffraction. b. atmospheric seeing. c. refraction. d. the focal length.

b. atmospheric seeing.

Clumps grow into planetesimals by a. attracting other clumps with opposite charge. b. colliding with other clumps. c. conserving angular momentum. d. gravitationally pulling in other clumps.

b. colliding with other clumps.

A grating is able to spread white light out into a spectrum of colors because of the property of a. reflection. b. dispersion. c. diffraction. d. interference.

b. dispersion.

The amount of angular momentum in an object does not depend on a. its mass. b. its temperature. c. its radius. d. its rotation speed.

b. its temperature.

The physical model of the Sun's interior has been confirmed by observations of a. sunspots and solar flares. b. neutrinos and seismic vibrations. c. sunspots and seismic vibrations. d. sample returns from spacecraft. e. neutrinos and positrons.

b. neutrinos and seismic vibrations.

When less energy radiates from a planet, its __________ increases until a new __________ is achieved. a. size; temperature b. temperature; equilibrium c. temperature; size d. equilibrium; size

b. temperature; equilibrium

The Sun rotates once every 25 days relative to the stars. The Sun rotates once every 27 days relative to Earth. Why are these two numbers different? a. Earth is smaller. b. The stars are farther away. c. Earth moves in its orbit during this time. d. The Sun moves relative to the stars.

c. Earth moves in its orbit during this time.

You are shopping for telescopes online. You find two in your price range. One of these has an aperture of 20 cm, and the other has an aperture of 30 cm. If aperture size is the only difference, which should you choose, and why? a. The 20 cm, because the image size will be larger. b. The 30 cm, because the image size will be larger. c. The 30 cm, because the light-gathering power will be better. d. The 20 cm, because the light-gathering power will be better.

c. The 30 cm, because the light-gathering power will be better.

The solar corona has a temperature of 1 million to 2 million K; the photosphere has a temperature of only about 6000 K. Why isn't the corona much, much brighter than the photosphere? a. The photosphere is closer to us. b. The magnetic field traps the light. c. The corona has a much lower density. d. The corona emits only X-rays.

c. The corona has a much lower density.

How does the speed of light in a medium compare to the speed in a vacuum? a. The speed in the medium is always faster than the speed in a vacuum. b. The speed in the medium may be faster or slower, depending on the medium. c. The speed in the medium is always slower than the speed in a vacuum. d. The speed is the same in both a medium and a vacuum, as the speed of light is a constant.

c. The speed in the medium is always slower than the speed in a vacuum.

If scientists want to find out about the composition of the early Solar System, the best objects to study are a. the Sun. b. the terrestrial planets. c. asteroids and comets. d. the giant planets.

c. asteroids and comets.

A planet in the "habitable zone" a. is far from the central star. b. is the same distance from its star as Earth is from the Sun. c. is at a distance where liquid water can exist on the surface. d. is close to the central star.

c. is at a distance where liquid water can exist on the surface.

Refraction is caused by a. two light beams interfering. b. light bouncing off a surface. c. light changing speed as it enters a new medium. d. light changing colors as it enters a new medium.

c. light changing speed as it enters a new medium.

In Figure 5.15, the red photons come from the transition from E3 to E2. These photons will have the _________ wavelengths because they have the _________ energy compared to the other photons. a. longest; most b. shortest; least c. longest; least d. shortest; most

c. longest; least

The solar neutrino problem pointed to a fundamental gap in our knowledge of a. nuclear fusion. b. hydrostatic equilibrium. c. neutrinos. d. magnetic fields.

c. neutrinos.

The direction of revolution in the plane of the Solar System was determined by a. the direction of the gravitational force within the original cloud. b. the amount of material in the original cloud. c. the direction of rotation of the original cloud. d. the plane of the galaxy in which the Solar System sits.

c. the direction of rotation of the original cloud.

Sunspots change in number and location during the solar cycle. This phenomenon is connected to a. the rotation rate of the Sun. b. the temperature of the Sun. c. the magnetic field of the Sun. d. the tilt of the axis of the Sun.

c. the magnetic field of the Sun.

Which of the following factors does not directly influence the temperature of a planet? a. the albedo of the planet b. the distance from the planet to the Sun c. the size of the planet d. the luminosity of the Sun

c. the size of the planet

The solar wind pushes on the magnetosphere of Earth, changing its shape, because a. the solar wind is so dense. b. the magnetosphere is so weak. c. the solar wind contains charged particles. d. the solar wind is so fast.

c. the solar wind contains charged particles.

Why would astronomers put telescopes in airplanes? a. to allow the telescopes to observe the full spectrum of light b. to get the telescopes closer to the stars c. to get the telescopes above the majority of the water vapor in Earth's atmosphere d. to be able to observe one object for more than 24 hours without stopping

c. to get the telescopes above the majority of the water vapor in Earth's atmosphere

In the proton-proton chain, four hydrogen nuclei are converted to a helium nucleus. This does not happen spontaneously on Earth because the process requires a. vast amounts of hydrogen. b. hydrostatic equilibrium. c. very high temperatures and densities. d. very strong magnetic fields.

c. very high temperatures and densities.

The two Keck 10-meter telescopes, separated by a distance of 85 meters, can operate as an optical interferometer. What is its resolution when it observes in the infrared at a wavelength of 2 microns? a. 0.2 arsec b. 0.01 arcsec c. 0.05 arcsec d. 0.005 arcsec

d. 0.005 arcsec

Two stars are of equal luminosity. Star A is 3 times as far from you as star B. Star A appears ______ star B. a. 1/3 as bright as b. 3 times brighter than c. the same brightness as d. 1/9 as bright as e. 9 times brighter than

d. 1/9 as bright as

When an electron moves from a higher energy level in an atom to a lower energy level, a. a redshifted spectrum is emitted. b. a continuous spectrum is emitted. c. a photon is emitted. d. a photon is absorbed.

d. a photon is absorbed.

Improved resolution is helpful to astronomers because a. they often want to look in detail at small features of an object. b. they often want to look at very distant objects. c. they often want to look at many objects close together. d. all of these answers are correct.

d. all of these answers are correct.

If we could increase the quantum efficiency of the human eye, it would a. increase the resolution of the human eye. b. allow humans to see a larger range of wavelengths. c. decrease the resolution of the human eye. d. allow humans to see better at night or in other low-light conditions.

d. allow humans to see better at night or in other low-light conditions.

As a blackbody becomes hotter, it also becomes __________ and __________. a. more luminous; redder b. less luminous; bluer c. less luminous; redder d. more luminous; bluer

d. more luminous; bluer

The structure of the Sun is determined by both the balance between the forces due to __________ and gravity and the balance between energy generation and energy __________. a. ions; loss b. solar wind; production c. pressure; production d. pressure; loss

d. pressure; loss

As energy moves out from the Sun's core toward its surface, it first travels by __________, then by __________, and then by __________. a. conduction; radiation; convection b. radiation; convection; conduction c. radiation; conduction; radiation d. radiation; convection; radiation

d. radiation; convection; radiation

The concept of disk instability was developed to solve the problem that a. Jupiter consists mostly of volatiles. b. there was not enough gas in the Solar System to form Jupiter. c. Jupiter-like planets migrate after formation. d. the early solar nebula likely dispersed too soon to form Jupiter.

d. the early solar nebula likely dispersed too soon to form Jupiter.

Energy is produced primarily in the center of the Sun because a. that's where neutrinos are created. b. the strong nuclear force is too weak elsewhere. c. that's where most of the helium is. d. the outer parts have lower temperatures and densities.

d. the outer parts have lower temperatures and densities.

The terrestrial planets and the giant planets have different compositions because a. the giant planets are much larger. b. the terrestrial planets have few moons. c. the giant planets are made mostly of solids. d. the terrestrial planets formed closer to the Sun.

d. the terrestrial planets formed closer to the Sun.

The advantage of an interferometer is that a. the light-gathering power is dramatically increased. b. the focal length is dramatically increased. c. diffraction effects are dramatically decreased. d. chromatic aberration is dramatically decreased. e. the resolution is dramatically improved.

e. the resolution is dramatically improved.