a. the sun's diameter is about 100 times that of earth and its surface temperature is more
than 5000 degrees celsius. it is too hot to be a solid or liquid, but is instead made of
la gaseous mix of charged particles
b. the
is the central region of the sun. under the force of gravity, hydrogen fuses
to form helium and releases large amounts of energy in the process. with a temperature
of about 15 million degrees celsius, the core is the hottest part of the sun
c. the
zone is the layer above the core energy produced in the core
radiates through this layer, which is so dense that it takes more than 100.000 years on
average) for a photon to escape
d. the
zone is the layer above the radiative zone. currents of plasma
actively transport energy through this region. it takes about a month (on average) for a
photon to move through this region
e. the
lis the visible surface of the sun it appears relatively smooth
except for occasional sunspots, an increase in the number, size, and complexity of these
sunspots suggests unrest beneath this layer.
f. the sun's atmosphere is composed of two layers-the
and the
--that are both hotter than the photosphere. the corona reaches
temperatures of more than 1 million degrees celsius.
2 the sun's energy
a. the sun formed more than_ billion years ago from a gigantic cloud of gas and dust.
b. nuclear fusion reactions are the source of the sun's steady output of energy. the
outward force of pressure created by this process is
inward force of the sun's gravity.
3. the electromagnetic spectrum
by the
a. hydrogen fuses into helium under the intense heat and pressure created by gravity. this
process releases energy in the form of
4. the dynamic sun
and
a. the sun's magnetic field is similar to earth's in that there is a
magnetic pole. magnetic field lines connect the two poles. during
periods of low solar activity, the magnetic field is
_ during periods of high
solar activity, the magnetic field is