chapter 8 astronomy

​Which of the natural forces bind atomic nuclei?

strong force

Nuclear fusion within the Sun proceeds step-by-step in a series of reactions called the neutron-neutron chain.

false

​Which is the correct order of the Sun's atmospheric layers, from the innermost to outermost?

\n ​photosphere → chromosphere → corona

​What is the average distance between the Sun and Earth?

1 AU

Which layer of the Sun's atmosphere is represented in the accompanying visual-wavelength image (Figure 8-2)?

corona

When the Sun generates its own energy, it uses weak forces to bind together atomic nuclei.

false

​Galileo proposed that the Sun is a rotating sphere after he ____.

measured different spectral lines of emission on different days

​How many nuclear reactions occur in a proton-proton chain?

three

​The corona is so dim that it is not visible in Earth's daytime sky.

true

​The _____ occurs when some of the energy in the convective motion of gas is converted into magnetic field energy.

dynamo effect

​What are the dark regions that give the Sun's photosphere a mottled appearance?

granules

The Babcock model of the solar magnetic cycle explains the sunspot cycle as primarily a consequence of the Sun's ____.

differential rotation

Which equation represents the overall nuclear fusion process of the Sun?

\n 41H →4He + energy

The temperature of the Sun is determined by measuring the __________ of sunlight.

spectrum

​Astronomers refer to the dark center of a sunspot as a(n) ____

umbra

​Helioseismology maps of rotation in the Sun's interior show that its internal gases rotate with equal periods.

false

​Why was the Davis experiment only able to detect one-third of the neutrinos originally predicted?

\n ​The neutrinos distributed evenly among three different flavors while traveling to Earth.

​What is released from the proton-proton chain and is immediately absorbed by the surrounding gas, thereby heating it?

gamma rays

During nuclear fusion, four hydrogen nuclei fuse into how many helium?​

one

​Nuclear fusion in the Sun is tremendously powerful.

false

​Of the following parts of the Sun, which is the hottest?

corona

​The upper chromosphere is hot enough to emit X-rays.

true

In order for nuclear fusion to occur, atomic nuclei must overcome the ____ by colliding violently.

Coulomb barrier

​The pink color of the chromosphere is produced by the combined light of three emission lines of hydrogen: ____.

red, blue, violet

​Granulation is caused by convection currents just below the photosphere.

true

What process on the Sun's photosphere does this figure (Figure 8-1) represent?

convection currents

​The Sun is a ball of hot gas held together by its own gravity.

true

​Which two elements are most abundant within the Sun?

hydrogen and helium

​Sunspot numbers follow a seven-year cycle.

false

​Astronomers can measure the magnetic fields of sunspots using the ____, which splits spectral lines into multiple components.

Zeeman effect

​What is the approximate average temperature of the Sun's surface?

5800 K

​What methodology do astronomers use to map the inside of the Sun?

helioseismology

​Why does the temperature of the corona rise with latitude?

Atoms within the corona become more ionized at higher altitudes.

Almost all the light we receive from the Sun escapes from underneath its photosphere.

false

​During the first reaction of the proton-proton chain of nuclear fusion, a weak force causes one of the protons to transform into a neutron and emit ____.

a positron and a neutrino

​Sunspots are parts of active solar regions dominated by magnetic fields that encompass all layers of the Sun's atmosphere.

true

Consider the complete magnetic cycle of sunspot activity on the Sun. Approximately how many years is this cycle?​

22 years

The corona can reach temperatures of up to ____.

\n ​2,000,000 K

​When mapping the interior of the Sun, astronomers must measure _____ as the photosphere moves up and down

doppler shifts

The solar wind can blow past Earth with speeds as high as 1000 km/s.

true

​Sunspots tend to occur in groups, or pairs, with the magnetic field around the pair resembling that around a bar magnet.

true

​The visible surface of the Sun is composed of solid matter.

false

Granules on the Sun's photosphere can be several thousand kilometers across.

true

​Astronomers often record solar images in the ____ part of the electromagnetic spectrum because the gaseous layers high in the Sun's atmosphere are very hot and emit most of their light at short wavelengths.

ultraviolet

​The layer above the chromosphere is the photosphere.

false

​What occurs on the surface of the Sun during a solar cycle minimum?

little to no sun spot activity

​Spicules can trigger communications blackouts and auroras on Earth.

false

​What causes granulation on the photosphere?

convection

​Granulation is evidence that energy in the photosphere ____.

flowing upward