Transcript Astronomy - Hewlett

Astronomy
The
Big Bang
What is the Big Bang
Theory?
• A scientific theory that states that
the universe formed from a gigantic
explosion that originated at a single
point.
• This explosion is called the Big Bang
and it occurred around 12-15 billion
years ago.
• The universe is still expanding from
the initial explosion.
Evidence of the Big
Bang
• In 1929 Edwin Hubble
discovered that distant galaxies
are moving away from us.
• He also discovered that the
further a galaxy is the faster it
is moving away.
• His evidence is based on the
doppler effect.
The Doppler Effect
• Is the observed change in frequency
of a moving object.
• Red Shift- if an object is moving
away from us, the waves will be
stretched causing a red shift.
• Blue Shift- if an object is moving
towards us, its waves will be
squished causing a blue shift.
1.) Do distant galaxies
have a red shift or a blue
shift?
2.) Do these galaxies have
a high or low frequency?
?
Answers
1. They have a red shift.
2. They will have a low frequency.
Where are stars born?
• Stars are born in a Nebula.
• Nebula- large cloud of gas and
dust, birthplace of stars.
Formation of the Solar
System
1. The nebula formed a spinning disc.
2. Gas in the center of the disc
collapses to form a protostar.
3. Temperatures increase until
nuclear fusion occurs, and a star is
born.
Nuclear Fusion- H+H=He + energy; this
is how stars produce light and
heat.
Formation of Solar
System Continued
4. The remaining gas and dust
formed the planets.
5. The solar system includes the
sun, planets, and belts of rock,
ice, and dust that orbit the Sun.
Questions to Ponder
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If a star is born, can it also die?
If a star can die, what makes it die?
What happens between the stars birth and death?
What is the next stage in our Sun’s life cycle?
Does every star go through the same exact life
cycle?
What is the fate of our Sun?
Which size stars live longer small or large?
How long is our star the sun expected to live?
Is our sun a large or small star?
Life Cycle of a Low to
Medium Mass Star
• 1. A star is born when Nuclear Fusion
begins in the stars core.
• 2. Stars will first burn Hydrogen and
become a Main Sequence Star.
• 3. When Hydrogen is used up the star will
burn Helium and become a Red Giant.
• 4. The star will then Nova(shed its outer
layers) and become a White Dwarf.
• 5. Once the star runs out of fuel it will
become a Black Dwarf.
Life Cycle of Massive
Stars
• 1. Main Sequence Star.
• 2. When hydrogen is used up the star
will expand and become a
Supergiant.
• 3. Then the star will Supernovaexplode.
• 4. After a Supernova the star will
either become a Black Hole, a
Neutron Star or a Pulsar.
Galaxy- group of a
billion stars
• 3 Types
• 1.) Spiral Galaxy- flat disc with arms spiraling out
of the center
• *This galaxy rotates.
• *Black Hole at its center.
• *Our Galaxy, the Milky Way.
• 2.) Elliptical Galaxy- looks like a flat ball; like a
football.
• *Most common galaxy.
• *Does not rotate.
• 3. Irregular Galaxy- does not have definite shape
The Milky Way Galaxy
(Birds Eye View)
Milky Way
(Side View)
Adromeda- the nearest
spiral galaxy
Large Magellanic Cloud
Small Magellanic Cloud
Elliptical Galaxy
The Siamese Twins
The Sombrero
The Polar Ring Galaxy