Download Section 7.3 - CPO Science

Laws of Motion and Energy
Chapter Seven: Gravity and
Space
• 7.1 Gravity
• 7.2 The Solar System
• 7.3 The Sun and the Stars
Investigation 7B
The Sizes of the Solar System
• How big is the solar system?
7.3 Stars
• A star is essentially
an enormous, hot ball
of gas held together
by gravity.
• The density at the
sun’s core is about
158.0 g/cm3.
This is about 18 times the
density of solid copper!
7.3 Why stars shine
• At high density and
pressure, nuclear
fusion occurs,
releasing tremendous
amounts of energy.
• Fusion reactions in the
sun combine hydrogen
to make helium.
7.3 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.
7.3 Types of stars
•
•
•
Stars come in a range
of sizes and
temperatures.
Blue giant stars are
hot and much more
massive than the sun.
Stars that are smaller
than the sun come in
two main categories,
dwarfs and neutron
stars.
7.3 Distances to the nearest stars
• One light year is the
distance that light
travels through
space in one year.
• A light year is a unit
of distance, not
time.
7.3 Temperature and color
• If you look closely at the stars on a clear night,
you might see a slight reddish or bluish tint to
some stars.
• This is because stars’ surface temperatures
are different.
7.3 Temperature and color
• Red stars are cooler than
white stars, and blue stars
are the hottest.
• White light is a mixture of all
colors at equal brightness.
7.3 Galaxies
• A galaxy is a huge
group of stars, dust,
gas, and other objects
bound together by
gravitational forces.
• The sun, along with an
estimated 200 billion
other stars, belongs to
the Milky Way galaxy.
7.3 Galaxies
•
The disk of the Milky Way is a flattened,
rotating system that contains young to
middle-aged stars, along with gas and
dust.
7.3 Distances between galaxies
•
•
The distances between stars are 10,000
times greater than the distances between
planets.
The distances between galaxies are a million
times greater than the distances between
stars.
7.3 Distances between galaxies
•
•
Figuring out the distance between galaxies is
one of the more difficult tasks in astronomy.
A faint object in the night sky could be a dim
object that is relatively nearby or a bright
object that is far, far away.
7.3 Distances between galaxies
•
•
The most reliable method for
estimating the distance to a
galaxy is to find a star
whose luminosity is known.
If the luminosity is known,
the inverse square law can
be used to find the distance
from the observed
brightness.
Astronomy Connection
Extraterrestrial Volcanoes
• There are active
volcanoes on Earth, but
did you know that a
moon of Jupiter is
considered the most
volcanically active place
in the solar system?
Activity
Sunspots
• Sunspots are large, dark
regions that appear on
the surface of the Sun.
• In this activity, you will
determine the diameter of
the Sun and the number
of sunspots on the Sun.