Download Mapping the Stars

Astronomy: The Original Science
• How did people in ancient times tell time?
• The studied the movement of stars, planets and the moon. They
watched as the seasons changed.
• Farmers learned the best time to plant and harvest crops by
watching the yearly cycles of time.
• What was built due to the fact of ancient people watching the
movement of objects in the sky?
• Observatories.
• What did the study of the night sky eventually become known as?
• The science of astronomy which is the study of the universe.
• What do we call the scientists that study the universe?
• astronomers
Mapping the Stars
Patterns in the Sky
When people in ancient cultures connected stars in
patterns they named sections of the sky based on
these patterns.
What are these patterns called?
Constellations
Constellations
What are constellations?
They are sections of the sky that contain
recognizable star patterns.
How did the following of the constellations help
ancient people?
By understanding the location and movement of
the constellations it helped them to navigate and
keep track of time.
Every star or galaxy is located within 1 of how
many constellations?
88
Leo the Lion
Horizon and Light Year
• What is the horizon?
• It is the line where the sky and the
Earth appear to meet.
• What is a light year?
• It is the distance light travels in
one year which is about 9.46
trillion kilometers
(88,179,380,564,073,582,184,704,018.81 sextillion miles)
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The Apparent Motion of
Stars
Why does the Earth appear to move across the sky?
It appears to move across the sky due to the Earth’s rotation.
Do the stars appear to move at night also?
Yes
All the stars we see at night appear to rotate around which star?
Polaris which is the North Star
Where is Polaris located?
Directly above the Earth’s North Pole.
Stars are actually moving in space, but since they are so distant ,
their movement is hard to see.
• Over time, due to this movement, the shapes of star patterns such
as the Big Dipper and other groups, change.
The Life
Cycle of Stars
• The Beginning and End of Stars
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How does a star enter its life cycle?
It enters the first stage as a ball of gas.
What pulls the gas and dust together into a sphere?
Gravity
What happens as the sphere becomes denser?
It gets hotter and the hydrogen changes to helium.
What is that process called?
Nuclear fusion.
What happens when a star dies?
Some of the material returns to space and combines with more gas
and dust to form new stars.
Different Types of
Stars
How are stars classified?
Size, mass, brightness, color,
temperature, spectrum, and age.
Main Sequence Stars
• After a star forms, it enters the second and
longest stage of its life cycle known as
what?
• Main sequence
• What happens during this stage?
• Energy is generated in the core of the star
as hydrogen atoms fuse into helium
atoms.
Giants and Supergiants
• After the main sequence stage a star can enter the third
stage of its life cycle.
• What can a star become in this stage?
• Red giant- a star that expands and cools once it uses all
of its hydrogen.
• What happens to the center of the star?
• It shrinks due to the loss of hydrogen.
• How big can red giants and supergiants become?
• Red giants 10 or more times bigger than the sun and
supergiants at least 100 times bigger than the sun.
White Dwarfs
• In the final stages of a star’s life cycle, it has the
same mass as the sun or smaller and is called a
white dwarf.
• A white dwarf is a small hot star that is the
leftover center of what?
• An older star.
• Does a white dwarf have hydrogen left at this
stage?
• No, therefore, it can no longer generate energy.
• How long can white dwarfs shine?
• Billions of years before they cool completely.
H-R Diagram
A Tool for Studying Stars
• The combination of research done between Danish astronomer
(Hertzsprung) and American astronomer (Henry Norris Russell)
on the brightness and temperature of stars resulted in a graph
called what?
• H-R diagram
• What does the diagram show?
• It shows the relationship between a star’s surface temperature
and its absolute magnitude (brightness).
• On the H- R diagram which color represents hot stars and
which color represents cool stars?
• Blue-hot on the left and cool-red on the right.
• Bright stars are at the ________ and dim stars are at the
_______
• Top/bottom
• What is the main sequence on the
diagram?
• It is the diagonal pattern where most stars
lie.
• A star spends most of its lifetime in the
__________ ____________.
• Main sequence
When Stars Get Old
SuperSupernovas
Massive blue stars use their hydrogen much faster
than stars like the sun do.
Blue stars do not have long lives.
What happens at the end of a blue stars life?
It may explode in a large, bright flash called a
supernova.
What is a supernova?
It is a gigantic explosion in which a massive star
collapses.
Supernova explosion
Neutron Stars and Pulsars
• After a supernova occurs, the materials in the
center of it are pushed together to form what?
• A new star
• What happens to the particles inside the star’s
core at this time?
• They are forced together to form neutrons.
• What is a neutron star?
• It is a star that has collapsed under gravity to the
point at which all of its particles are neutrons.
• What is a spinning neutron star called?
• Pulsar
Pulsar and Neutron Star
Black Holes
• What is a black hole?
• It is an object that is so massive that even light
cannot escape its gravity.
• They form sometimes from the leftovers of a
supernova that has collapsed.
• How are black holes found by astronomers?
• Sometimes gas or dust from a nearby star will
spiral into the black hole and give off X rays to
help them detect their existence.
X-Rays From Black Holes
Galaxies
• What are galaxies?
• Large groups of stars, dust, and gas.
• How many stars does the largest galaxy
contain?
• More than a trillion.
• Who began to classify galaxies by their shapes
in the 1920’s?
• Edwin Hubble (astronomer that developed the
Hubble Space Telescope)
• How did he classify the galaxies?
• By their shapes.
Spiral Galaxies
What is a spiral galaxy?
It is a galaxy with a bulge at the center
and spiral arms.
What are the spiral arms composed of?
Gas, dust and new stars.
The Milky Way
• Astronomers think we live in a spiral
galaxy for what reason?
• It is hard to see what type we live in but by
observing other galaxies and making
measurements inside our galaxy,
astronomers are led to believe our solar
system is a spiral galaxy and is called The
Milky Way.
The Milky Way
Elliptical Galaxies
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Elliptical Galaxies are massive blobs of stars.
What percentage of all galaxies are massive blobs of stars?
About 1/3
Some look like _______ and others are stretched out.
Spheres
These galaxies usually have very _______centers.
Bright
They have very little ______ and ______.
Dust and gas
What age stars are elliptical galaxies composed of?
Old.
Why do few new stars form here?
There is so little free-flowing gas
Irregular
Galaxies
• Hubble called the leftover galaxies that
really did not have a shape irregular
galaxies.
Contents of
Galaxies
• What are galaxies composed of?
• Billions of stars and some planetary
systems.
• What do some of these stars form?
• Gas clouds and star clusters
Gas Clouds (Nebula)
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What is the Latin word for cloud?
Nebula
What is a nebula?
It is a large cloud of gas and dust.
Some nebulas glow, some absorb light
and hide stars.
• Some reflect starlight and produce some
amazing images.
• Eagle Nebula
Crab Nebula
Star Clusters
• What are globular clusters?
• Groups of old stars that looks like a ball.
• How many stars can be in a globular
cluster?
• Up to one million
• Where are these clusters located?
• They are located in a spherical halo that
surrounds spiral galaxies such as the
Milky Way.
Globular cluster
• Open cluster-group of closely grouped
stars (many blue stars)
Quasars
• What are quasars?
• They are starlike sources of light that are
extremely far away.
• They are among the most powerful energy
sources in the universe.
• What do some scientists think may cause
quasars?
• Massive black holes in the cores of some
galaxies.