Download Galaxies - Wallkill Valley Regional High School

How We See Ourselves In
The Universe: A Look At The
Galaxies That Surround Us
How High Can You Count?
Our solar system contains the following items:
1 star (the sun)
8 planets
1-3 dwarf planetoids
a few hundred natural satellites (moons)
gases, asteroids, dust, etc.
Well, Guess What?
Our solar system is only one of billions of star systems
that make up the Milky Way Galaxy, which is only one of
several dozen galaxies that makes up our Local Cluster, and
our Local Cluster group is only one of many in a collection
called superclusters…
Welcome to the Universe!
What are galaxies?
Galaxies contain millions or billions of stars held together by gravity
Gravity holds galaxies together in clusters
Clusters of galaxies can form even larger groups called superclusters
How do we see galaxies?
We can see our own Milky Way without the use of a telescope
Spyglasses let us see further at sea and into the skies
Telescopes (far-seeing) allow us to see distant galaxies
With new technology comes new discovery
Optical Telescopes
Radio Telescopes
Very Large Array (VLA) New Mexico
Refracting Telescope
Nice, France
Reflecting Telescope,
Los Angeles, CA
- Uses combinations of
- Uses combinations of
lenses to see distant
light sources
mirrors to see distant
light sources
- Detects radio signals from space
Infrared Telescopes
Hubble Telescope (1990)
Hubble repairs (2001)
X-Ray Telescopes
Chandra Observatory (1999)
Messier 100
Tarantula Nebula in
Large Magellanic Cloud
Pillars of Creation,
Eagle Nebula
Crab Nebula caused
by 1054 supernova
Supernova 1604
Spiral Galaxies
Milky Way
NGC 7331
“Pinwheel”
- A flat, rotating disc of mainly young (blue) stars and interstellar matter
- A central “bulge” of mainly older (red) stars
- A spherical “halo” of stars, including many in globular clusters
- A super-massive black hole at the center of the central bulge
NGC 1672
Andromeda
NGC 1365
Elliptical Galaxies
ESO-325
M 59
NGC 4125
- Have no spiral arms and are spherical or egg shaped
- Contain mostly older (red) stars and little interstellar matter
- Range from dwarf to giant galaxies based on number of stars
M 32
M 105
M 87
Irregular Galaxies
IC 10
M 82 “The Cigar”
NGC 1569
- Lack regular shapes and do not have well-defined structure
- Some contain large amounts of interstellar matter, others do not
- More dwarf irregular galaxies than large ones
- Most irregular galaxies found near spiral or elliptical galaxies, so
gravity may affect shapes
Large Magellanic Cloud
NGC 4449
NGC 1427A
Are galaxies stationary?
- Galaxies are on the move, due to
gravity, inertia and early forces
at the time of the Big Bang
- If the spectral lines in light from a galaxy
shift toward the red end of the spectrum,
the galaxy is moving away from us (red shift)
- If the spectral lines in light from a galaxy
shift toward the blue end of the spectrum,
the galaxy is moving toward us (blue shift)
Hubble Deep Field,
13 million years ago
Artistic depiction of
a quasar; a new galaxy?