STAR GROUPS

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STAR GROUPS

• Of the non-Hollywood variety

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BINARY STARS

• Binary Stars are two stars revolving around each
  other which appear as one. (One third of the
  stars we see)

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STAR CLUSTERS

• Are groups of stars which stay close together

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OPEN CLUSTER

• An irregularly shaped group of stars

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GLOBULAR CLUSTER

• A spherically shaped group of stars

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GALAXIES

• Vast systems of stars

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ELLIPTICAL GALAXIES

• Oval shaped with a thick center (like the
  mirrored image of a fried egg)

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SPIRAL GALAXIES

• Huge bright central disc with radiating arms.

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IRREGULAR GALAXIES

• Neither elliptical or spiral shaped.

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Our galaxy, the MILKY WAY GALAXY, is spiral shaped
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The Doppler Effect

• Astronomers can tell if stars are moving by
  studying their spectra. The DOPPLER EFFECT is
  the apparent change of wavelength when the object
  is moving toward or away from the observer.

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One Shift Two Shift

• RED SHIFTS

• BLUE SHIFTS

Wavelengths from a receding star (moving away
from us) spectral lines get longer.
Wavelengths from an approaching star spectral
lines get shorter (Blue to you!)
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THE BIG BANG THEORY

• States that the universe began as a single cosmic
  explosion about 15 billion years ago.

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Background Radiation

• Energy left over from the Big Bang that is evenly
  spread out throughout the universe.
• This background radiation is one observation that
  supports the Big Bang Theory.

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After the Big Bang

• Gravity began to affect matter racing in every
  direction.
• The clumps formed into huge clusters of matter.
• These clumps became the galaxies of the universe.

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HUBBLES LAW

• The farther away the galaxy, the faster it is
  receding (moving away) from the earth.

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Galaxies seem to be racing away from the center
of the Universe.

• Every galaxy seems to be moving away from Earth.
• After examining the Red Shift that appears from
  distant galaxies astronomers conclude the
  universe is expanding at tremendous speeds.

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Expanding Universe

• If the universe is expanding, then the objects
  near the very edge of the universe are the oldest
  objects in the universe.
• The most distant known objects in the universe
  are over 12 billion light years from the Earth
  and they are

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Quasars

• An enormously bright object at the edge of our
  universe which emits massive amounts of energy.
  In an optical telescope, they appear point-like,
  similar to stars, from which they derive their
  name
• quasar quasi(something like) stellar(star).

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Quasars

• Most studied and mysterious objects in the
  universe.
• Too small to be galaxies, they give off more
  energy than 100 or more galaxies combined.

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Quasar
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Three Pieces of Evidence Supporting the Big Bang

• The presence of Background Radiation
• The observation of the galaxies spreading away
  from the center of the universe (Red Shift)
• Quasars at the edge of the universe first formed
  objects

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What Happens Next?

• Astronomers feel that the Big Bang theory leads
  to two possible futures for the Universe.

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Open Universe

• Galaxies will continue racing outward (continue
  to expand). All of the stars will die off as the
  last of their energy is released. There will be
  nothing left, total emptiness.

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Closed Universe

• Gravitational attraction between the galaxies
  will cause the movement away from each other to
  slow and, eventually come to a halt. The
  gravitational pull will begin to pull the
  galaxies back to the center of the universe.

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Closed Universe cont.

• All of the matter and energy will again come
  close together and end in a central area
  (possibly no larger than a dime). Then another
  Big Bang will occur and the formation of the
  universe will begin all over again.

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Um I think we may have been here before.

• This restructuring may occur once every 80 to 100
  billion years.