Download Galaxies - Where Science Meets Life

CHARACTERISTICS OF THE
UNIVERSE
What is a Solar System?
A star and everything that
travels around it.
What is a star?
Large ball of gas that
generates its own energy by
fusion
(H+H He); held together by
its own gravity.
The Pistol Star
What is a Galaxy?
A collection of stars and
interstellar gas/dust; stars
stay close due to gravity.
What is a Nebula?
A hot cloud of dust &
gaseous elements/compounds;
nurseries for stars.
Eskimo or
Clownface
Nebula
What is a planet?
Non-luminous, larger than
asteroid, illuminated by
light from a star.
Hierarchy of the Universe
Universe
Largest
Galaxy
Solar System
Star
Planet
Smallest
GALAXIES
They come in all shapes and sizes.
Galaxies
Elliptical
Stars
Galaxies
Spiral
Irregular
Sun
Milky Way
Solar
System
Planets
Minor
Objects
Spiral
 Spiral-shaped
 Central bulge with
arms extending
outward.
 Lots of gas and dust.
 Many established stars.
The Milky Way
Now, the Milky Way is considered a Bar Galaxy!
Elliptical
 Rounded shape, no
defined spiral arms.
 Longer in one
direction, like a
football.
 Very little gas or dust.
 No recent star
formation within
galaxy.
Irregular
 No definite shape
 Many new stars
constantly forming.
Galaxy Formation
Can you classify the galaxy
just by looking at it?
Stars
 Galaxies are made up of many
stars. The largest galaxies have up
to a trillion stars. Although they
are not counted, scientist can
estimate from the size and
brightness of a galaxy, the
number of sun-sized stars the
galaxy may have.
The Life Cycle of a Star
The Sun
 The Sun is classified as a yellow,
average star. What is the next
stage in its life cycle?
Classifying Stars
 In 1911, a Danish astronomer named Ejnar
Hertzsprung compared the temperature and
brightness of stars on a graph. Two years
later, an American astronomer named Henry
Norris Russell created similar graphs. Their
research was combined to form what is now
called the Hertzsprung-Russell diagram, or HR diagram.
H-R Diagram
 The graph shows the relationship
between a star’s surface temperature
and its absolute magnitude. The
absolute magnitude is the actual
brightness of a light. This is found on
the y-axis of the H-R diagram.
H-R Diagram
 Temperatures of stars are calculated
by the color difference that is visible.
The hottest stars are blue and the
coolest stars appear red. The
temperature of a star is found on the
x-axis of the H-R diagram.
Remember!
 The color of light that we see is based
on the wavelength and frequency of
the light.
Light Spectrum
H-R Diagram
Red and Blue Shift
 Doppler Effect- Is the change of frequency of
a wave for an observer moving relative to the
source of the wave.
Red and Blue Shift
 This change is consistent for both
sound and light waves.
 Red shift- Objects appear more red as
they move further away.
 Blue shift- Objects appear more blue
as they move closer.
How does red shift support the
theory of the Big Bang?
Red Shift and the Big
Bang
 Scientist can measure the red shift of
light from distant galaxies. The red
shift indicates that the stars are
moving away from a central point in
the universe at a certain speed. This
supports the theory of the Big Bang in
that the universe started from a
central spot.