Astronomy Unit Review BMS 8th Grade Science Magee Life Cycle

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Astronomy Unit Review

• BMS 8th Grade Science
• Magee

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Life Cycle of a Star
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NEBULA
_____________ A dense cloud of gas and dust
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The nebula begins to contract due to __________
and the pressure and temperature increase and
becomes a ________________.
gravity
PROTOSTAR
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When the temperature gets hot enough,
_______________ begins and a _______ ____________
star is born.
fusion
MAIN SEQUENCE
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A star loses ____________during fusion as energy
is released. This decreases the stars gravity.
A star will expand, becoming a ___________
____________, when the outward force of
________________ is greater than the inward force
of ______________.
mass
RED GIANT
fusion
gravity
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As the fuel runs out in a star, _________ slows
down. When the ______________ force of fusion is
less than the ____________ force of gravity, the
star will shrink in size, becoming a _________
____________.
fusion
outward
inward
WHITE DWARF
White Dwarf
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SUPERNOVA
explosion
A ___________________ is an _________________
that marks the end of a very massive stars life.
When it occurs, the exploding star can outshine
all of the other stars in the galaxy in total for
several days and may leave behind only a crushed
core.
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The life cycle of stars depends on their
mass. Small and medium stars become
__________________ once they die. Larger stars
become novae and die as ____________
BLACK DWARVES
NEUTRON STARS
A neutron star is an imploded core of an exploded
star made up almost entirely of neutrons. A
teaspoon of their material would weigh more than
all of automobiles in the U.S. together
The most massive stars become supernovae and die
as ______________________
BLACK HOLES
A black hole is an extremely massive remnant from
which light can not escape
http//chandra.harvard.edu/photo/2004/rxj1242/inde
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Why do larger/hotter stars burn their fuel faster
and live shorter lives than the Sun?
Large, more massive stars have much more
_____________ than the sun. This greater
internal pressure causes fusion reactions to
occur __________. This causes the largest stars
to burn their fuel, and eventually run out, much
more ______________. Larger stars live shorter
_____________. Bigger stars are brighter and
hotter due to the rapid rate of __________.
gravity
quickly
quickly
lives
fusion
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Where do we get the elements?
All stars spend the majority of their lives
fusing __________ into ________________ the main
sequence.
hydrogen
helium
When all of the __________ in the central regions
is converted to helium, the star will begin to
burn helium into _______________.
hydrogen
carbon
sun
Stars heavier than about 5 times the mass of the
______ can do this with no problem they burn
_____________, and then _______________, and then
_____________, _______________, silicon, and so
onuntil Iron.
hydrogen
helium
carbon
oxygen
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energy
Iron is the lightest element that doesnt release
__________ when you attempt to fuse it together.
You actually end up with less energy than you
started with! So instead of generating pressure
to hold up the outer layers, the iron fusion
actually takes it out of the core. Thus, there
is nothing left to combat ________________ from
the outer layers. The result ___________!
gravity
collapse
This implosion (___________) happens very, very
quickly about 15 seconds. During the collapse,
the nuclei in the outer parts of the star are
pushed together, so close that elements heavier
than __________ are formed.
supernova
iron
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Measuring Distances in Space

• Parallax
• Astronomical Unit
• Light Year

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Galaxies

• Galaxy
• A large group of stars, gas, and dust that is
  held together by gravity
• 3 types of galaxies
• Spiral, Elliptical, and Irregular

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Galaxies

• Have spiral arms that wind outward from the
  center, resembling a pinwheel.
• Why can astronomers see the spiral arms of the
  Andromeda Galaxy more clearly than the spiral
  arms of the Milky Way Galaxy?

Spiral Galaxy
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Galaxies

• Have billions of stars but little gas and dust
• Typically filled with old stars because without
  gas and dust, new stars are no longer forming

Elliptical Galaxy
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Galaxies
Elliptical Galaxy
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Galaxies

• Have an irregular shape
• Typically smaller than elliptical and spiral
  galaxies
• Have bright, young stars and lots of dust and gas
  to form new stars

Irregular Galaxy
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Galaxies
Irregular Galaxy
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• Have your ever looked up into the night sky and
  scanned the stars for the Greek hunter Orion?
  Orion is a ___________ -- a pattern of stars that
  represents mythological characters. What appears
  as groups of stars that are close together are
  actually great distances apart. Each star has a
  specific brightness and a location that can be
  calculated from Earth

constellation
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Optical Telescopes

• A ____________ uses a lens to collect and focus
  light. Light enters through a lens. The light
  is bent toward a single point called the focal
  point. Because the light is bent, the image
  forms upside down. An eyepiece lens magnifies
  the upside-down image for viewing. The telescope
  can be focused by changing the distance between
  the two lenses.

Refracting telescope
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Optical Telescopes

• A ____________ uses a curved mirror instead of a
  lens to collect and focus light. N some models,
  one end of the main tube is open. At the other
  end of the tube is a large, curved mirror. The
  large mirror collects, reflects, an focuses light
  to a small, flat mirror near the open end. The
  small mirror reflects the light to an eyepiece
  lens

Reflecting telescope
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