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Origins of the
Universe
Mrs. Kettering
8th Grade Science
2011
How old is the Universe?
• There is a lot of controversy over the age of
our universe
• The most recent information came in April
of 2007. From this study, the age of the
universe is most likely 15-20 billion years.
• Keep in mind that as technology and our
understanding of the universe expands,
that estimate may change.
Theories: Origins of the Universe
Theory #1: Big Bang Theory
• States that everything began together
at a point and a big explosion
occurred that caused everything to
move apart.
• Theory states that galaxies are
rapidly moving apart to this day
• Therefore, universe is ever-expanding
Theories: Origins of the Universe
Theory #2: Red Shift
• The spectrum of a star (or galaxy) reveals
whether is it moving toward or away from the
Earth
• If absorption lines are shifted slightly toward
one end of the spectrum, it is an indication
that the galaxy is moving relative to Earth.
Theories: Origins of the Universe
Theory #2: Red Shift
• Light reaching us from distant galaxies has its
absorption lines shifted toward the red end of the
spectrum which is referred to as the Red Shift –
this means the galaxies are moving away from
Earth
• If the absorption lines were shifted toward the
violet end of the spectrum (which there is
currently NO evidence of), the galaxy would be
moving toward us
The Red Shift
This image shows the shift on the spectrum
as the galaxy is moving further away
Theories: Origins of the Universe
Theory #3: Oscillating Theory
• Combines the Big Bang and Big Crunch
theories (Red and Blue Shift Theories)
• The universe will expand until it cannot
expand any more (Big Bang) and will then
begin to contract (Big Crunch) … this will
lead to another Big Bang and another
universe.
Doppler Effect
• The top image
shows a galaxy
that is NOT
moving relative
to Earth.
• The middle
image shows a
galaxy moving
AWAY from
Earth
• The bottom
image shows a
galaxy moving
TOWARD Earth.
Notice the shift on the
spectrum for each possibility
Theories: Origins of the Universe
Theory #4: Steady-State
• States that although the universe is
expanding, the amount of matter is
continuously increasing as well
• Therefore, the average density of
matter is staying relatively steady, and
the look of the universe does not
change
Galaxies: Introduction
• Galaxy – an organized system of
hundreds of millions to thousands of
billions of stars, sometimes mixed with
interstellar gas and dust.
• Our Sun and Solar System are part of
the Milky Way Galaxy
• Galaxies often appear to be distinct but
fuzzy patches of light
Classification of Galaxies
• In the 1920s, Edwin Hubble
devised a classification of
galaxies:
1.Disc-shaped Galaxies
2.Elliptical Galaxies
3.Irregular Galaxies
Spiral Galaxies
• Disc-shaped (Spiral) Galaxy: flat disks
that look like a spiral, with long arms
winding toward a bright bulge at the
center
• About 77% of the observed galaxies in
the universe are disc-shaped galaxies
• Milky Way Galaxy (our galaxy) is a discshaped galaxy
Spiral Galaxies
Elliptical Galaxies
• Elliptical Galaxy: have an
ellipsoidal shape and a smooth,
nearly featureless brightness
profile
• Very little interstellar matter (gas
or dust)
• No prominent internal structure
Elliptical Galaxies
Irregular Galaxies
• Irregular Galaxy: not disk-like or
ellipsoidal and have no nucleus;
chaotic, irregular appearance
• They have little symmetry in their shape
• Most irregular galaxies were once spiral
or elliptical galaxies that have been
distorted and deformed by gravitational
action from other, nearby galaxies
Irregular Galaxies
Sun
• closest star to Earth – the next closest star is
39,900,000,000,000 km away (4.2 light yrs)
• Medium size
• Yellow
• Main Sequence Star
• 150,000,000 Km (93 Million miles) away.
• 4.5 - 5 billion years old
• Will last about another 5 billion years
• Located near the edge of our disc shaped
galaxy – The Milky Way
Important Space Vocabulary:
• Comets - Rocky material made of gas dust and
ice that orbit the sun
• Meteors - Space Rocks known as shooting stars
when they enter the Earth’s atmosphere.
Become meteorites when they hit the Earth’s
surface
• Asteroids - Small rocky bodies known as minor
planets
Orbit the sun mainly between Mars and Jupiter
(asteroid belt)
Stars
• Gigantic spheres of gas held together by
gravity
• Generate huge amounts of energy
because of nuclear reactions of hydrogen
and other elements.
• Radiate electromagnetic radiation.
–Light, heat and other forms of energy
• There are 100 billion stars in our own
galaxy!
Classifying Stars
Class
Color
Surface Temp.
(degrees Celsius)
Elements detected
Examples of
stars
O
B
Blue
Above 30,000
Helium
10 Lacertae
Blue-white
10,000 - 30,000
Helium and
Hydrogen
Rigel, Spica
A
F
Blue-white
7,500 - 10,000
Hydrogen
Vega, Sirius
Yellow-white
6,000 - 7,500
Hydrogen and
heavier elements
Canopus,
Procyon
G
Yellow
5,000 - 6,000
Calcium and other
metals
The sun, Capella
K
Orange
3,500 - 5,000
Calcium and
Molecules
Arcturus,
Aldebaran
M
Red
Less than 5,000
Molecules
Betelgeuse,Anta
res
Hertzsprung-Russell Diagrams
• Shows the relationship between
a star’s surface temperature and
absolute magnitude/luminosity
(brightness)
• Used to study the lives of stars
–Most stars lie along the main
sequence portion of the diagram
HR-Diagram
HR-Diagram
HR-Diagram
Stages of a Stars Life Cycle
Important Star Vocabulary
• Nebulae - Giant clouds of gas and dust in
space. Where new stars are formed.
• Supernova gigantic explosion in which a
massive star collapses
– Occurs after a massive star uses up its
fuel source
• Black Hole an object that is so massive
that light cannot escape its gravity
– Believed to be the center of most galaxies
– Remnants of a supernova
– Astronomers can detect black holes by
using X-ray telescopes
Light Years
• Unit of measurement for distances in space
• The distance that light travels in one year.
• Light travels at about 300,000 km/sec.
– 186,000 miles/sec
• One light year is equal to 9.46 trillion km
(9,461,000,000,000).
– 5.87 trillion miles (5,870,000,000,000)
• Light travels faster than anything else known
to man.
GALAXY FOLDABLE
• Read Pages 720-721 and/or use your notes to
complete the following
Galaxy Type 1
•Description
•Example
Galaxy Type 2
•Description
•Example
Galaxy Type 3
•Description
•Example
Picture
Picture
Picture
representation representation representation
of Galaxy
of Galaxy
of Galaxy