Name: __________________________ Date: _____________



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.
When two protons and two neutrons combine to form 4He, it is found that this helium nucleus is less massive than the sum of the four original particles used to construct it. What is the significance of this?
A.
The lost mass is transferred into energy.
B.
The mass is lost through friction.
C.
The “lost” mass can be accounted for by the masses of the particles emitted as radioactive decay during the interaction.
D.
The mass disappears without a trace.


4.
How much hydrogen is converted into helium and energy in the Sun each second?
A.
600 million tons
B.
6 billion tons
C.
600 tons
D.
6 tons


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.
Approximately where is the Sun in terms of its total lifetime?
A.
It is about halfway through its life.
B.
It is only 1/10 of the way through its life.
C.
It is about 3/4 of the way through its life.
D.
It is about 1/4 of the way through its life.


7.
A positron is
A.
a positively charged neutrino.
B.
a positively charged electron.
C.
a charged neutron.
D.
a positively charged particle with intermediate mass between a proton and an electron.


8.
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.


9.
The phrase “hydrostatic equilibrium” in the Sun refers to
A.
the balance of gas pressure outward and magnetic forces inward.
B.
the creation of one helium nucleus for the “destruction” of every four hydrogen nuclei.
C.
the balance of gas pressure inward and heat outward.
D.
the balance of gravity inward and gas pressure outward.


10.
Where is the Sun's energy generated?
A.
the core
B.
the photosphere
C.
the chromosphere
D.
the corona


11.
Which of the three ways by which heat energy can be transmitted from one place to another—radiation, conduction, convection—is important in the solar interior below the surface of the Sun?
A.
radiation and convection
B.
conduction and radiation
C.
conduction and convection
D.
radiation alone, by photons of energy


12.
The two most important processes by which energy is transported from the core of the Sun to the photosphere are
A.
conduction and convection.
B.
radiation and convection.
C.
radiation and conduction.
D.
radiation and neutrino emission.


13.
Just outside the radiation zone lies the
A.
convection zone.
B.
conduction zone.
C.
photosphere.
D.
corona.


14.
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.


15.
The temperature at the center of the Sun, where thermonuclear processes take place, is approximately
A.
about 4500 K, as shown by holes in the Sun.
B.
1.5 million K.
C.
6000 K.
D.
1.5 × 107 K.


16.
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.


17.
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).


18.
How many neutrinos pass through your outstretched hand (10 × 10 cm) from the Sun every second, day and night?
A.
1 trillion or 1012
B.
1 trillion or 1012 in daytime—almost none during the night because they are stopped by Earth
C.
10 billion or 1010
D.
only a few hundred, otherwise we would notice them


19.
A neutrino produced in the nuclear furnace in the core of the Sun
A.
can penetrate easily through both the gas of the Sun's interior and the solid Earth.
B.
can penetrate easily through both the gaseous Sun's interior and the solid Earth but will be easily stopped by chemicals containing chlorine.
C.
can penetrate easily through the Sun's gaseous interior but will be stopped just below the surface of the solid Earth.
D.
can penetrate easily through the Sun's interior but will be deflected away from Earth by its magnetic field.


20.
Which of the following particles or types of radiation will provide the most direct information on the processes of nuclear fusion that are occurring in the solar core?
A.
protons in the solar wind and from solar flares
B.
neutrinos
C.
highly penetrating X-rays
D.
visible light from the photosphere


21.
Why should you never look directly at the Sun?
A.
It uses up valuable time.
B.
Looking directly at the Sun causes blindness.
C.
It can lead to baldness.
D.
It is bad for the complexion.


22.
The photosphere is the level of the Sun from which most of the visible radiation we see originates. The temperature of the base of the Sun's photosphere is roughly
A.
600 K.
B.
6000 K.
C.
60,000 K.
D.
one million K.


23.
Which part of the Sun is the origin of most of the light we see?
A.
the core
B.
the photosphere
C.
the chromosphere
D.
the corona


24.
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


25.
The chemical composition of the surface layers of the Sun is determined primarily by
A.
examination of samples of meteorites that originated in the Sun.
B.
satellite measurements of the solar wind.
C.
theoretical modeling and computer calculation.
D.
spectroscopy.


26.
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.


27.
In order from lowest to highest, what are the names of the three layers in the Sun's atmosphere?
A.
photosphere, chromosphere, corona
B.
chromosphere, photosphere, corona
C.
corona, chromosphere, photosphere
D.
photosphere, corona, chromosphere


28.
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.


29.
Which part of the Sun has the lowest density?
A.
the core
B.
the photosphere
C.
the chromosphere
D.
the corona


30.
How did astronomers first detect the high temperatures in the corona of the Sun?
A.
by measuring the brightness of the corona in visible (white) light
B.
by direct measurements using space probes
C.
by observing emission lines of highly ionized elements like iron
D.
by observing the effects the high temperature has on Mercury and Venus


31.
A coronal hole shows up most prominently in photographs taken at what wavelengths?
A.
radio wavelengths
B.
visible light
C.
X-ray
D.
the specific color of the first Balmer line of hydrogen, Hα, at 656.3 nm


32.
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.


33.
Coronal holes are thought to be the source of
A.
the solar wind.
B.
powerful loops of magnetic field linked to active regions.
C.
influence on human behavior (e.g., astrology).
D.
dust released from the Sun.


34.
The solar wind is
A.
a violent explosive expansion of specific regions of the Sun's atmosphere at certain times.
B.
another name for the electromagnetic radiation coming from the Sun.
C.
the inflow of matter onto the Sun under gravitational attraction.
D.
a gentle outflow of solar material, mostly protons and electrons, always moving outward from the Sun.


35.
Sunspots are
A.
cooler regions of the Sun's high corona.
B.
the shadows of cool, dark curtains of matter, hanging above the solar surface.
C.
cooler, darker regions on the Sun's surface.
D.
hotter, deeper regions in the Sun's atmosphere.


36.
Where on the Sun do sunspots occur?
A.
the core
B.
the photosphere
C.
the chromosphere
D.
the corona


37.
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!


38.
Sunspots appear dark because they
A.
are coronal holes.
B.
are cooler than the surrounding surface.
C.
are regions from which the light is prevented from escaping by strong magnetic fields.
D.
have a different chemical composition than the surrounding surface.


39.
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.


40.
How can we characterize the rotation of the Sun?
A.
differential rotation, with the equator rotating faster than the poles
B.
like a solid body (all parts rotating equally)
C.
in a banded pattern, with alternating bands of fast and slow rotation
D.
differential rotation, with the equator rotating more slowly than the poles


41.
What is the rotation period of the Sun?
A.
about four rotations per month
B.
about two rotations per year
C.
about one rotation per day
D.
about one rotation per month


42.
How does the number of sunspots on the Sun vary with time?
A.
They vary irregularly, with no periodicity.
B.
relatively regularly, with a period of about 11 years
C.
They increase and decrease regularly in number at exactly 11-year intervals.
D.
They increase and decrease every year as Earth revolves around the Sun.


43.
The Zeeman effect refers to
A.
the brightening of sunlight near sunspots.
B.
the drift of sunspots across the solar disk.
C.
the shift of spectral lines because of solar rotation.
D.
the splitting of spectral lines when magnetic fields are applied to atoms.


44.
What is a typical magnetic field strength inside a sunspot?
A.
a million times stronger than Earth's magnetic field
B.
a few thousand times stronger than Earth's magnetic field
C.
1/100 of the strength of Earth's magnetic field
D.
a few times stronger than Earth's magnetic field


45.
Sunspots are caused by
A.
dark clouds hanging over the surface, above the magnetic field regions.
B.
the impact of meteoroids and comets on the solar surface.
C.
coronal holes darkening the surface.
D.
differential rotation and its effect on weak magnetic fields.


46.
What is a plasma?
A.
a region where the Hα line causes the Sun's surface to glow red, like blood
B.
a region where the intense magnetic field has caused the Sun's atoms to line up in a rigid array
C.
a gas-like mixture of ions and electrons
D.
an unusual mixture of charged particles in which the positives and negatives do not occur in equal numbers


47.
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.


48.
What is a filament on the Sun?
A.
a prominence seen in silhouette against the photosphere
B.
a sunspot that has been stretched by solar differential rotation
C.
a spicule seen in profile near the edge of the Sun's limb
D.
a plage near the end of its life, when it is fading away


49.
Solar flares occur at what positions on the solar disk?
A.
only at the polar regions
B.
only in a narrow band along the solar equator
C.
only within sunspot groups
D.
only in coronal holes


50.
What are the most energetic eruptive events to occur on the Sun?
A.
thermonuclear explosions
B.
erupting prominences
C.
coronal mass ejections
D.
solar flares



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