Section 27.1
Download
Report
Transcript Section 27.1
UNIT NINE: Matter and Motion
in the Universe
Chapter 26 The Solar System
Chapter 27 Stars
Chapter 28 Exploring the Universe
Chapter Twenty-Seven: Stars
27.1 The Sun
27.2 Stars
27.3 The Life Cycle of Stars
Chapter 27.1 Learning Goals
Explore the properties of the Sun.
Identify unique zones of the Sun and describe
what happens in each area.
Discuss applications of solar energy.
27.1 The Sun
The Sun is is a giant,
hot ball of gas held
together by gravity.
The Sun is mediumsized compared with
other stars in the
universe.
Approximately 1 million
planet Earths could fit
inside the Sun!
27.1 The Sun
Gravity squeezes the
density of a star so
tightly in the core that
the electrons are
stripped away and the
bare nuclei of atoms
almost touch each other.
Nuclear fusion occurs.
27.1 The Sun
In the process, huge
amounts of energy are
given off.
Because of its mass,
the Sun’s gravitational
force is strong enough
to hold the entire solar
system in orbit.
27.1 Anatomy of the sun
The apparent surface of
the Sun that we can see
from a distance is
called the photosphere,
which means “sphere
of light.”
Just above it is the
chromosphere.
This is a very hot layer
of plasma, a highenergy state of matter.
27.1 Anatomy of the sun
The corona is the
outermost layer of the
sun’s atmosphere,
extending millions of
kilometers beyond the sun.
Sunspots are areas of gas
that are cooler than the
gases around them.
27.1 Features of the sun
Occasionally, large
“loops” of gas
called prominences
can be seen
jumping up from
groups of
sunspots.
27.1 Features of the sun
Solar wind is an
electrically charged
mixture of protons and
electrons that cause
magnetic storms.
Auroras, called the
northern lights, occur
when layers of our
atmosphere are
energized by solar
winds.
27.1 Solar energy
Solar energy is a term that refers to
radiant energy from the Sun.
The radiant energy of the Sun reaches
Earth in the form of electromagnetic
waves.
We can use solar energy to heat
buildings and generate electricity.
27.1 Solar energy
Buildings that use
passive solar heating
are designed to trap
sunlight.
Glass traps warm air,
causing a
“greenhouse effect.”
27.1 Solar energy
Photovoltaic (or PV)
cells are devices that
convert sunlight
directly into electricity.
Solar cells are found
on calculators,
watches, or certain
outdoor light fixtures.
27.1 More about the Sun’s energy
In 1905, Albert Einstein proposed that matter
can be converted into energy.
His famous equation shows how huge
amounts of energy can be created from a
smaller mass.
27.1 More about the Sun’s energy
The amount of this
energy from the Sun that
reaches the outer edge
of Earth’s atmosphere is
known as the solar
constant.
The accepted value is
1,386 watts per square
meter (W/m2), or about
thirteen 100-watt light
bulbs per square meter
of surface.
Optional* Investigation 27C
Efficiency of a Solar Cell
Key Question:
How can we use energy from the sun to
generate electricity?