Name: __________________________  Date: _____________

1.	The approximate temperature of the visible surface of the Sun is	
A)	10,000 K.	
B)	2000 K.	
C)	4300 K.	
D)	5800 K.	

2.	Granulation on the surface of the Sun is caused by	
A)	differential rotation of the Sun.	
B)	nuclear fusion processes occurring just below the surface.	
C)	magnetic field disturbances above the solar surface.	
D)	convective currents carrying heat from beneath the surface.	

3.	What is the reason why the edge of the Sun's visible disk is darker than the center?	
A)	The gases near the edge are in regions where stronger magnetic fields inhibit the emission of light.	
B)	We see more deeply into the Sun near its edge and the gas is cooler at these deeper levels.	
C)	We see into shallower layers of the Sun near the edge; the gas is cooler there and so emits less light.	
D)	We see into shallower layers into the Sun near the edge, and, because the gas is less dense there, it emits less light.	

4.	What are the names of the three layers in the Sun's atmosphere, in order from lowest to highest?	
A)	Corona, chromosphere, photosphere	
B)	Photosphere, chromosphere, corona	
C)	Photosphere, corona, chromosphere	
D)	Chromosphere, photosphere, corona	

5.	What is the solar wind?	
A)	The constant flux of photons from the Sun's visible surface	
B)	Material from the corona, accelerated out into space	
C)	The storm of waves and vortices on the Sun's surface generated by a solar flare	
D)	The circulation of gases in the chromosphere, between the equator and the poles of the Sun	

6.	Sunspots are	
A)	cooler, darker regions on the Sun's surface.	
B)	the shadows of cool, dark clouds of matter hanging above the solar surface.	
C)	cooler regions of the Sun's high corona.	
D)	hotter, deeper regions in the Sun's atmosphere.	

7.	How can we characterize the rotation of the Sun?	
A)	Differential rotation, with the equator rotating more slowly than the poles	
B)	In a banded pattern, with alternating bands of fast and slow rotation to produce the sunspots	
C)	Differential rotation, with the equator rotating faster than the poles	
D)	Like a solid body, with all parts rotating at the same rate	

8.	The sunspot cycle on the Sun is	
A)	the regular movement of a relatively constant number of sunspots from the poles to the equator of the Sun over an 11-year period.	
B)	a somewhat irregular, but always present, cycle of build-up and decay of sunspot numbers.	
C)	an irregular build-up and decay in the number of sunspots averaging about 11 years, which occasionally fails for a time when no spots appear.	
D)	an extremely regular build-up and decay in the number of sunspots, with a precise period of 11.3 years.	

9.	Why are sunspots cooler than the rest of the Sun's surface?	
A)	Sunspots, unlike the rest of the Sun, are made of plasma, and plasmas are difficult to heat.	
B)	Sunspots mark the pathways along which neutrinos escape from the Sun.  Neutrinos move so quickly that they deposit very little energy along their paths.	
C)	Sunspots occur where the magnetic field lines return into the Sun carrying smaller amounts of heat energy from the thin solar atmosphere.	
D)	Sunspots mark the places where the magnetic field lines penetrate the Sun's photosphere.  The hot solar plasma beneath is repelled from these field lines and thus inhibit the flow of heat to the surface at these points.	

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

11.	Where on the Sun do solar flares occur?	
A)	Only in a narrow band along the solar equator	
B)	Only at the polar regions	
C)	Only in coronal holes	
D)	Only within sunspot groups	

12.	The solar wind is	
A)	the inflow of matter onto the Sun under gravitational attraction.	
B)	ionized hydrogen gas and electrons orbiting the Sun between its surface and the planet Mercury.	
C)	a violent, explosive expansion of specific regions of the Sun's atmosphere at certain times.	
D)	a gentle outflow of solar material, mostly protons and electrons, that is always moving outward from the Sun.	

13.	What is the energy source for the Sun?	
A)	Thermonuclear fusion in the core	
B)	Radioactive decay of the nuclei of heavy elements	
C)	Primordial heat, left behind from when the Sun first formed	
D)	Heat released by gravitational contraction as the Sun slowly shrinks	

14.	From which fusion reaction does the Sun derive its power?	
A)	4He  O	
B)	2H  He	
C)	3He  C	
D)	4H  He	

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

16.	To what do the words “hydrostatic equilibrium” in the Sun refer?	
A)	The balance of gas pressure outward and magnetic forces inward	
B)	The balance of gravity inward and gas pressure outward	
C)	The creation of one helium nucleus for the “destruction” of every four hydrogen nuclei	
D)	The balance of gas pressure inward and heat outward	

17.	The order of the layers or parts of the Sun, as radius increases, is	
A)	radiative zone, convection zone, chromosphere, photosphere, and corona.	
B)	radiative zone, convection zone, photosphere, chromosphere, and corona.	
C)	corona, chromosphere, convection zone, photosphere, and radiative zone.	
D)	radiative zone, convection zone, corona, chromosphere, and photosphere.	

18.	Before 1998, what results were obtained in the detection of solar neutrinos?	
A)	No neutrinos were detected at all.	
B)	About six times as many neutrinos were observed as were expected from theoretical models of the Sun.	
C)	The neutrinos were about twice as energetic on average as was predicted by theoretical models of the Sun.	
D)	Only about 1/3 of the expected number of neutrinos were observed, compared to theoretical models of the Sun.	

19.	Recent solar neutrino experiments have confirmed the suspicion that the explanation for the apparent shortfall in neutrino detection rates over the last 30 years was because	
A)	the Sun does indeed produce only 1/3 of that predicted by earlier theoretical models; these models require major modification.	
B)	2/3 of the neutrinos from the Sun had been absorbed by material between Sun and the Earth.	
C)	2/3 of the solar neutrinos had transformed into types of neutrinos that were undetectable by old detection techniques.	
D)	the detectors had been faulty; 2/3 of the neutrinos had been missed by the detectors.	

20.	The corona of the Sun has a temperature that is	
A)	about 10 K because it merges with cold interstellar space.	
B)	noticeably less than the photosphere, between 1000 to 2000 K.	
C)	about 1 to 2 million K.	
D)	about the same as the photosphere, about 6000 K.	

Answer Key

1.	D	
2.	D	
3.	C	
4.	B	
5.	B	
6.	A	
7.	C	
8.	C	
9.	D	
10.	D	
11.	D	
12.	D	
13.	A	
14.	D	
15.	D	
16.	B	
17.	B	
18.	D	
19.	C	
20.	C