Chapter 16: The Sun

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R. equals the solar radius, or radius of the Sun as a whole, equal to 696,000km.


The Sun has a center layer called _______________ _________ ______, that extends to a distance of .25 R.

Thermonuclear Energy Core.

The second layer of the Sun is called the ______________ _______ and it is from .25 R. to .71 R.

Radiative Zone.

The third layer of the Sun is called the ____________ _______, from .71 R. to 1.0 R., the edge of the star.

Convection Zone.

__________________ takes place in a ______ extending from the Sun's center to about 0.25 solar radius

Hydrogen-Fusion; Core.

The core is surrounded by a __________ _____ extending to about 0.71 solar radius. In this zone, energy travels ________ through radiative diffusion

Radiative Zone;Outward.

The radiative zone is surrounded by a rather opaque __________ _____ of gas at relatively low temperature and pressure. In this zone, energy travels outward primarily through ___________.

Convection Zone; Convection.

There are two methods of energy transport that occur within the Sun, _____________ and ____________ ______________.

Convection; Radiative Diffusion.

During _______________, hot and cool gases in the Sun circulate, hot gasses would _______ while cooler gasses would ________ back to the center. Physical movement of gasses transports heat energy outward in a star.

Convection; Rise; Sink.

In ______________ ______________, photons are constantly created at the hot core in a thermonuclear inferno, and then migrate toward the cooler surface where they escape.

Radiative Diffusion.

Composition of the Sun (mass): 74% Hydrogen, 25% _____________, 1% other elements.


Composition of the Sun (# of atoms): 92.1% _______________, 7.8% _______________, 0.1% other elements.

Hydrogen; Helium.

Temperature ___________ as the height of the chromosphere increases. ___________ tends to follow the Sun's magnetic field, which arches tens or thousands km into the corona. When two arches come in contact the magnetic fields will rearrange, causing a tremendous amount of energy to be released into the atmosphere, maintaining the high temperature of the _____________ and _______.

Increases; Plasma; Chromosphere and Corona.

The outflow of gas from the corona is the _______ _______. It is composed almost entirely of electrons and nuclei of hydrogen and __________.

Solar Wind; Helium.

The Sun's power comes from its core, where thermonuclear reactions convert ___________ into __________ in a process called ____________ ___________, which releases energy that heats the Sun and gives it luminosity. The steps of hydrogen fusion are called the __________-__________ chain.

Hydrogen; Helium; Hydrogen Fusion; Proton-Proton.

The causes of "active" Sun are dramatic features that appear periodically such as massive ___________, regions of concentrated _______________ __________, and _____________.

Eruptions; Magnetic Field; Sunspots.


Irregularly shaped dark regions in the photosphere.

The __________ cycle is an 11 year period with the most sunspots at a time called _____________ _______________ and the Sun is almost devoid of sunspots at the _____________ _________________.

Sunspot; Sunspot Maximum; Sunspot Minimum.

The Sun's ____________ ________ pushes away hot plasma causing a localized region of cooler gas glowing less brightly, a sunspot. With the Sun's polarity reversing itself every 11 years, it takes ____ sunspot cycles for the magnetic pattern to repeat itself, the ___-______ ________ ________.

Magnetic Field; Two; 22-Year Solar Cycle.

Each sunspot has a dark central core called the __________, and a brighter border called the ______________.

Umbra; Penumbra.

A _________ _______ resembles a giant bar magnet with a northern and southern magnetic pole at the ends. As the group moves with the Sun's rotation the spots in the front are called ___________ ___________ and the spots following behind are called ______________ ____________. The preceding members each hemisphere have a _________ that matches the hemispheres polarity in which they are in.

Sunspot Group; Preceding Members; Following Members; Polarity.

More active regions of the Sun are _______________ and __________.

Prominences and Flares.

_______________ are bright, arching columns of gas called that can extend for thousands of km above the photosphere.


Violent, eruptive events on the Sun that occur in complex sunspot groups are called _________ _________.

Solar Flares.

The Proton-Proton Chain is a nuclear process called ____________ _________, in which 4 hydrogen atoms go through a sequence of nuclear reactions and produce one ____________ atom.

Hydrogen Fusion; Helium.

The net effect of the proton-proton chain is each time the reaction takes place a small fraction of the initial mass is ______. This _____ mass is then converted to _________ that is 10^7 times larger than a typical chemical reaction. In bulk this energy is what has powered the ______ for billions of years.

Lost; Lost; Energy; Sun.

Energy is produced from a __________ reaction because the __________ from the two remaining protons motion contributes to the heat of the Sun.

Fusion; Energy.

Solar Neutrino Problem:

The Proton-Proton chain creates neutral non active atoms called Neutrinos that do not interact a lot with matter. Large neutrino detectors were built to discovery how many neutrino's passed through Earth, but the result was always about 1/3 of what should have been detected. The lack of correct number of neutrinos was called the Solar Neutrino Problem.

Solution to the Solar Neutrino Problem:

The solution to this problem was that are actually three types of neutrinos, only one of which the Sun creates, and the experiments were built to detect that type. But neutrinos can change their type and they do this one the way to Earth. So they built the Sudbury Neutrino observatory that could detect all 3 types of neutrinos, and the correct numbers were there.

Everyday examples of Conduction:

Placing a poker in a fire and holding it there, after a period of time the end not in the fire heat up as well. Slowest method. Particles do not move and are heated by the particles next to it.

Everyday examples of Convection:

Boiling water in a pot, the water at the bottom heats up, expands, and rises as the cooler water at the top contracts and sinks. Requires the material to transfer and the material itself to move.

Everyday examples of Radiative Diffusion:

Rapid cooling when it is a clear night. Earth emits infrared radiated photons which travel at the speed of light out into space. The energy is transferred by light or radiation. No material is required. Fastest method.

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