THE
UNIVERSE
How it started...
 THE BIG BANG THEORY
 At one time everything was compacted
together in an extremely small, dense, ball
of energy, and then 10 – 15 billion years
ago something caused it to EXPLODE.
 Because of this, nebulas, stars, galaxies,
planets and other bodies formed.
 The universe is still EXPANDING today.
Components of the Universe
 NEBULA
 A large cloud of dust and gas where stars
are born.
Components of the Universe
 Stars
 4 kinds of stars
 White Dwarfs
 Main Sequence – our Sun
 Giants
 SuperGiants
 They are classified using their size and color.
 Our Sun is a MEDIUM sized star that gives off
a YELLOW color.
Stars
 Use the H–R Diagram to classify the stars
O
B
A
Spectral Class
F
G
K
M
Things to remember about the H–R diagram




Hottest stars are BLUE
“Coldest” stars are RED
The Sun is Yellow
Oh Be A Fine Girl, Kiss Me – to remember spectral class
O
B
A
Spectral Class
F
G
K
M
Our Sun
 The sun appears so large to us
because it is the closest star to
Earth.
 It is many thousands of times
closer to Earth than any other
star.
Components of the Universe
 GALAXIES
 A large group of stars, solar systems, and
gas and dust.
 We live in the MILKY WAY Galaxy.
Galaxies
 There are 3 types of galaxies...
 Spiral Galaxy
 Spiral shaped; Milky Way is a spiral galaxy
 Elliptical Galaxy
 Oval/Circular shaped; contains old stars
 Irregular Galaxy
 No obvious shape
Milky Way Galaxy
 Our solar system is located on an outer arm of the galaxy.
Components of the Universe
 Other celestial bodies...
 Asteroids
 Comets
 Satellites
 An artificial or natural body that revolves
around another object in space.
 Artificial satellite – Hubble Telescope
 Natural satellite – The Moon
Light Years
 The Universe is so large and galaxies
and objects are so far apart that
scientists use Light Years to measure
distances between them.
Light Years
 Speed of Light is 300,000 km/second
 In 1 year, light can travel 9,500,000,000,000 km
 OR 9.5 trillion km
 The closest star to the sun is 4 light years
away or 38,000,000,000,000 km away.