1.	What is the Sun's energy source? A. primordial heat left over from the release of gravitational energy when the Sun first formed B. radioactivity C. thermonuclear fusion in the core D. heat released by gravitational contraction

2.	What process provides the power for the Sun? A. fusion of helium into carbon B. fission of uranium to form lead C. emission of neutrinos D. fusion of hydrogen into helium

3.

Thermonuclear fusion reactions in the core of the Sun convert four hydrogen nuclei into one helium nucleus. The helium nucleus has A. less mass than the four hydrogen nuclei, the lost mass becoming energy in an amount given by E = mc2. B. the same mass as the four hydrogen nuclei, because the mass of any product has to equal the mass of the sum of its parts by the law of conservation of matter. C. an undetermined amount of mass that depends on the temperature at which the reaction occurs. D. more mass than the four hydrogen nuclei, because energy is produced in the reaction, and this energy adds the extra mass, m = E/c2.

4.

Hydrogen "burning" by fusion reactions occurs only in the deep interior of the Sun (and other stars), because this is the only place in the Sun where A. there is sufficient hydrogen. B. the density is sufficiently low for the high temperature atoms to build up enough energy to collide and undergo fusion. C. the temperature is low enough and the density is high enough to allow hydrogen atoms to collide with each other often enough for fusion to occur. D. the requisite conditions of high temperature and high density occur.

5.	How much longer can the Sun continue to generate energy by nuclear reactions in its core? A. about 500,000 years B. about 50 billion years C. about 5 billion years D. about 5 million years

6.

A positron is A. an antielectron, similar to a normal electron but with inverse properties, including a positive electrical charge. B. another name for a proton, or a positively charged hydrogen nucleus. C. a charged neutron. D. a positively charged neutrino, having positive charge and very small or zero mass.

7.	What happens to the positrons produced by the nuclear reactions in the core of the Sun? A. They collide with electrons, producing energy. B. They collide and stick together to form helium. C. They combine with neutrons to form protons. D. They escape from the Sun into space.

8.

The Sun has existed for a very long time without change in its size, appearance, or behavior. This means that it must be in hydrostatic equilibrium. Under these conditions, which two parameters must be in exact balance within the Sun? A. numbers of hydrogen and helium nuclei B. hydrogen gas pressure and helium gas pressure C. inward force of gravity and outward gas pressure D. magnetic field and force of gravity

9.	Of the three ways in which energy is transported in nature (radiation, conduction, convection), which two are important in the Sun? A. The statement is wrong—all three are equally important in the Sun. B. radiation and convection C. convection and conduction D. radiation and conduction

10.	The mechanism at work when energy is transmitted by convection is A. the successive exchange of radiant energy between atoms. B. the passage of radiation through a gas. C. the fusion of hydrogen nuclei into helium nuclei. D. the mass motion of hot gases.

11.

Energy is transported from the center of the Sun to the surface A. by radiation in the central thermonuclear core and convection through the rest of the interior. B. mostly by convection but with radiation in the outer layers. C. by convection in the central thermonuclear core and radiation through the rest of the interior. D. mostly by radiation but with convection in the outer layers.

12.

From the center outward, the order of the layers or parts of the Sun is A. radiative zone, convection zone, corona, chromosphere, photosphere. B. radiative zone, convection zone, chromosphere, photosphere, corona. C. corona, chromosphere, convection zone, photosphere, radiative zone. D. radiative zone, convection zone, photosphere, chromosphere, corona.

13.

The temperature of the Sun throughout its radius and including its atmosphere A. is almost constant from the center to the surface but falls abruptly just above the visible surface. B. decreases outward from the center, but increases several times at certain specific radial distances from the center, before decreasing to match the temperature of interplanetary space. C. decreases outward from the center, but then increases again. D. decreases continuously outward from the center, gradually merging into the cold of the interplanetary medium.

14.	Where is most of the mass of the Sun concentrated? A. It is spread uniformly through the Sun. B. in the inner core C. in the photosphere D. in the convective zone

15.

The neutrino is A. a tiny particle that interacts very weakly with matter, with extremely low or zero mass and no charge. B. another name for the neutron, a component of almost all atomic nuclei, with a mass close to the proton and no charge. C. another name for a photon of very high energy, i.e., short wavelength electromagnetic radiation, with great penetrating power. D. a massive but very elusive nuclear particle that carries most of the energy generated in the core of the Sun to the surface, but that then decays to release electromagnetic radiation (i.e., light).

16.	What happens to the neutrinos produced by the nuclear reactions in the core of the Sun? A. They collide and stick together with protons to form helium nuclei. B. They escape from the Sun into space. C. They combine with protons to form neutrons. D. They collide with electrons, producing energy.

17.	What name is given to the visible "surface" of the Sun? A. corona B. chromosphere C. prominence D. photosphere

18.	What causes the granular appearance of the surface of the Sun? A. the regular impact of meteoroids and comets on the solar surface B. differential rotation of the surface layers C. thermonuclear fusion in its interior D. convective motion under the solar surface

19.

If granulation on the Sun's surface is a result of convective motion below it, and material is upwelling at the centers of granular cells and returning in the regions between cells, what is the expected temperature distribution across a granular cell? A. The center of a cell will be cooler than the edges. B. Alternate cell centers will be hot and cold, with the edges at an intermediate temperature. C. Temperature will be uniform across the cell. D. The center of a cell will be hotter than the edges.

20.

The appearance of the visible spectrum of the Sun, when its light is separated in its component colors, is A. a uniform continuous spectrum with no structure. B. a spectrum containing many dark absorption and many bright emission lines on a continuous background. C. a continuous bright spectrum, crossed by thousands of dark absorption lines. D. a spectrum consisting only of a few bright emission lines.

21.	What is the name of the layer of the Sun's atmosphere that appears as a pinkish ring just outside the visible disk of the Sun during a total solar eclipse? A. the chromosphere B. the convective zone C. the photosphere D. the corona

22.	The temperature of the corona of the Sun A. is about the same as that of the photosphere, 5800 K. B. is about twice as hot as the photosphere, 12,000 K. C. is very cool, because it is farthest from the heat source. D. is very hot—about 106 K.

23.

Why is the solar corona so much hotter than the photosphere? A. Energy is carried upward through the chromosphere by convective gas motion. B. The corona absorbs part of the light passing through it from the photosphere. C. The high-speed solar wind passes through it and some of it is stopped, depositing energy. D. Energy is carried upward through the chromosphere by magnetic fields.

24.	What is the solar wind? A. the storm of waves and vortices on the Sun's surface generated by a solar flare B. the constant flux of photons from the Sun's visible surface C. the circulation of gases between the equator and the poles of the Sun D. the Sun's outer atmosphere streaming out into space

25.	What is the lifetime of a typical sunspot? A. from a few hours to a few months B. from a few years to a few decades C. 11 years D. Here today, gone tomorrow!

26.	What is the structure of a typical large sunspot? A. an irregular dark area of uniform darkness B. a dark center surrounded by a less dark area C. a roughly circular, dark region with a lighter central area D. usually round and of uniform darkness

27.

The rotation of the Sun is A. fastest at the equator, slowest at mid-latitudes, rising to intermediate speeds near the poles. B. fastest at mid-latitudes, slower at the equator, and slowest near the poles. C. fastest at the equator, slower at mid-latitudes, and slowest near the poles. D. slowest at the equator, faster at mid-latitudes, and fastest near the poles.

28.

What specific physical effect was used to verify the existence of intense magnetic fields in sunspots? A. observation of ionized atoms in the region of the sunspots B. the Zeeman effect, the splitting of spectral absorption lines C. the measurement of relative strengths of spectral absorption lines from various atoms D. Doppler shift of light from sunspots

29.

What is the character of the sunspot cycle? A. Sunspots increase and decrease in number over 11 years within a band of solar latitude between 10° and 30°, with no discernible dependence of sunspot latitude upon time. B. Starting at sunspot minimum, new spots appear uniformly over the Sun but gradually, new spots become concentrated at midlatitudes as they increase and then decrease in number. C. Starting at sunspot minimum, new spots appear close to the equator, followed by newer spots farther from the equator until, when numbers decrease, they grow and decay at high latitudes. D. Starting at sunspot minimum, spots first appear far from the equator, followed by new spots appearing successively closer to the equator as they increase in number and finally, spots form close to the equator as numbers begin to decrease.

30.

How does the Sun's overall magnetic field behave? A. The northern and southern hemispheres have opposite magnetic polarity, and this polarity reverses every 11 years. B. Magnetic polarity is randomly distributed over the Sun, while the strength of the magnetic field increases and decreases with an 11-year cycle. C. The northern and southern hemispheres have the same magnetic polarity, and this polarity reverses every 11 years. D. The poles of the Sun have the opposite magnetic polarity from the equator, and this polarity reverses every 11 years.

31.

Which recently discovered fact about the Sun might have some bearing on climate changes and the overall weather on Earth? A. Solar wind seems to originate in cooler regions of the corona, the coronal holes. B. There are far fewer neutrinos emitted from the Sun than are predicted. C. The Sun's surface is oscillating up and down every 5 minutes. D. The Sun's overall energy output depends upon the 11-year sunspot cycle.

32.

What causes sunspots? A. Magnetic fields inhibit the emission of radiation from atoms in the solar surface. B. Magnetic fields below the photosphere pull gas down, creating holes in the photosphere. C. Differential rotation on the Sun creates vortices, or eddies, which are cooler and darker than the rest of the solar surface. D. Magnetic fields breaking through the photosphere inhibit gas motion where the field is strong, lowering the amount of heat transferred to the surface.

33.	An arching column of gas suspended over a sunspot group is called A. a coronal hole. B. a prominence. C. a flare. D. a spicule.

34.

Solar flares, the violent eruptive events on the Sun, occur most frequently A. over single, isolated, but large sunspots. B. in or above complex sunspot groups. C. within solar coronal holes, from which the solar wind originates. D. along the solar equator at positions aligned with Jupiter's position, caused by tidal disturbance on the Sun.

35.

Which of the following is NOT a consequence of a coronal mass ejection event from the Sun, if the mass ejection is aimed toward the Earth? A. disruption to radio transmission and electrical power systems on Earth B. damage to and even destruction of satellite electronics and power systems C. major health hazard for astronauts in orbit around Earth and particularly on the Moon D. a major hurricane

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