Download Stars, Galaxies & Universe

Stars, Galaxies &
Universe
Chapter 3
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Tools of Astronomy
• Constellations are
groups of stars that
form a pattern.
• The electromagnetic
spectrum is made of
radio waves, infrared
radiation, visible light,
ultraviolet radiation, xrays, and gamma
rays.
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Refracting Telescope
• Refracting telescope
collects light using
lenses.
• The lenses bend the
light to the focal point.
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Reflecting Telescope
• Reflecting telescope
uses a mirror to
collect the light.
• A concave mirror
bends the light inward
to a focal point.
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Radio Telescope
• Radio telescopes
collects radio waves.
• The collector is a
concave dish.
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Observatory
• The building that
houses a telescope is
called an observatory.
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Other Tools of Astronomy
• Telescopes have
been put into space
on satellites & space
stations.
• Spectrographs gather
information about
stars such as a star’s
composition &
temperature.
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Characteristics of Stars
• A galaxy contains
hundreds of billions of
stars.
• The universe contains
billions of galaxies.
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Distances to Stars
• A light year is the
distance light travels in
year.
• Astronomers often use
parallax to measure
distances to nearby stars.
• Parallax is the apparent
change in position of an
object when you look at it
from different places.
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Classifying Stars
• Stars are classified by
size, temperature, and
brightness.
• Temperature of a star is
indicated by color, hot
stars are blue & cooler
stars are red.
• Apparent brightness is
the brightness of a star as
observed from earth.
• Absolute magnitude is the
brightness of a star
observed at the distance
of 10 parsecs.
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Hertzsprung-Russell Diagram
• H-R diagram is a
graph of the Milky
Way galaxy.
• Surface temperature
is graphed on the xaxis.
• Absolute magnitude is
graphed on the yaxis.
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Types of Stars
• Blue super giants have a
high brightness and high
temperature.
• Red giants & super giants
have a high brightness
and low temperature.
• White dwarfs have a low
brightness and high
temperature.
• 90% of all stars appear
on the Main Sequence
going from the upper right
to the lower left corner.
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Birth of a Star
• A star begins as a
cloud of gas and dust
called a nebula.
• Gravity pulls the gas
and dust together into
a protostar.
• A star is born when
the contracting gas
and dust becomes so
hot that nuclear fusion
begins.
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Length of Life of a Star
• More massive stars
live short lives of
millions of years.
• Less massive stars
live long lives of
billions of years.
• The sun will live for 910 billion years.
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During the Life Cycle of a Star
• Stars fuse hydrogen
into helium during
most of their lives.
• After all the hydrogen
has been fused into
helium, the star fuses
helium into carbon,
carbon into oxygen
and then oxygen into
iron.
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Death of a Star
• Stars use up their
hydrogen and expand
their atmosphere.
• Stars that are less than
1.4 solar masses will
shrink to a white dwarf.
• Stars between 1.4 -3.0
solar masses will produce
a supernova and leave a
neutron star.
• Stars more than 3.0 solar
masses will produce a
supernova and collapse
into a black hole.
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Star Systems
• Most stars are members
of groups of two or more
stars called star systems.
• Star systems with two
stars are called double
stars or binary stars.
• Binary eclipsing stars are
stars where one star
blocks the light from
another.
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One of the greatest advancements in astronomy
was the telescope. Which is the correct order of
advancements?
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D. Radio- reflectingrefracting
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Why do astronomers measure interstellar
distances in light years instead of kilometers or
miles?
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Miles and kilometers are
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help me!
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Which of the following correctly shows the age
progression of an average star?
A.
Main sequence→White
Dwarf→Red Giant
→Nebula
Red Giant →White
Dwarf →Main Sequence
→Nebula
Nebula →Main
Sequence →Red Giant
→White Dwarf
White Dwarf →Red
Giant →Main Sequence
→Nebula
B.
C.
D.
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What is the next likely stage of a
protostar?
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Super Giants
Nova
Main Sequence
Neutron Star
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Galaxies
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Galaxies are a group
of billions of stars.
Type of galaxies are
1. Elliptical
2. Spiral
3. Irregular
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Elliptical Galaxy
• Old galaxy.
• Contains red star that
are old.
• No gas or dust.
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Spiral Galaxy
• Middle aged galaxy.
• Contains blue stars.
• Has some dust and
gas.
• Our Milky Way is a
spiral galaxy.
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Irregular Galaxy
• Unorganized
collection of stars.
• Made of very young
stars.
• Has a great deal of
gas and dust.
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History of the Universe
• Edwin Hubble
discovered that the
farther away a galaxy
is from us, the faster it
is moving away from
us.
• Stars moving away
from us shows a red
shift.
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Big Bang Theory
• Big Bang Theory
suggest that billions
of years ago, the
universe was small,
hot and dense and
then the universe
exploded.
• The universe formed
in this enormous
explosion about 10 to
15 billion years ago.
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Formation of the Solar System
• The solar system
formed 5 billion years
ago.
• The solar system
formed from a giant
cloud of gas and dust,
or nebula.
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Future of the Universe
• The universe may
continue to expand.
• Gravity may pull the
universe back
together.
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What type of galaxy is shown in the
picture?
A. Irregular
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B. Spiral
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C. Elliptical
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D. I have no idea … I need help!!!
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Review Questions
• What are the three types of galaxies?
• elliptical, spiral & irregular
• Distances between stars are measured in
units called _______.
• light years
• Stars begin as a cloud of gas & dust
known as a __________.
• nebula
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Review Questions
• What does the length of life of a star depends
on?
• mass of the star
• What is the name of our galaxy?
• Milky Way
• What type of galaxy is the Milky Way?
• spiral
• What is the name of the theory of the creation of
the universe?
• Big Bang
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Review Questions
• What type of tools are used to study the
universe?
• telescope
• Which type of telescope uses mirrors?
• reflecting
• Which type of telescope uses lenses?
• refracting
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Review Questions
• What indicates how hot a star is?
• color of the star
• During nuclear fusion, what does
hydrogen fuse into?
• helium
• What is graphed on the H-R diagram?
• brightness & temperature
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Review Questions
• What is the brightness of a star as seen
from earth?
• apparent brightness
• What is the brightness of a star that is
seen at a standard distance of ten
parsecs?
• absolute magnitude
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Review Questions
• What process is used to measure the
distance of nearby stars?
• parallax
• What type of telescope collect
electromagnetic waves other than light?
• radio telescope
• How long ago did the Big Bang occur?
• 10-15 billion years ago
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Review Questions
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•
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What are patterns of stars in the sky called?
Constellations
What is the building called that has a telescope?
Observatory
Which type of galaxy has red stars and no gas
or dust?
• elliptical
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Review Questions
• Which type of galaxy has blue stars and
some gas & dust?
• spiral galaxy
• Galaxies are classified by their _______.
• shape
• Who proposed that the universe is
expanding?
• Hubble
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Review Questions
• What evidence do we have that the
universe is expanding?
• red shift
• What happens to a small star at its death?
• white dwarf
• What happens to a very large star at its
death?
• Supernova to a black hole
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Practice Extended Answer
Questions
• Describe the life cycle of a star.
• What are the three types of telescopes and how
are they different?
• Explain the H-R diagram.
• How does the mass of a star affect the length of
life of a star?
• How do the different types of galaxies compare?
• Explain the Big Bang Theory.
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