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This kinesthetic activity models the life of a
small to medium size star, such as our sun. Each person
involved in this activity represents a bit of the material that goes into making such a
star. As the activity begins everyone is dancing or moving
around freely--just bits of matter that are hanging out in some particular spot in space.
As these bits of matter come close to one another they start clumping
together more and more, due to gravity. After a while
this matter is clumped tightly enough to form a star. In our activity
the participants at the edges form a ring facing inward, as the outer shell of the
star, with their hands raised to represent the inwardly directed force of gravity.
The participants in the center face outward, representing the core
of the star, with their hands also raised to represent the energy generated by the
fusion of hydrogen at the center of the star. These two forces
remain in balance for most of the stars life. We call this a main
sequence star. Eventually the star runs out of hydrogen to
fuse in the core. And the balance of gravity and energy from fusion is broken.
When this happens gravity wins and the participants in the core
of the star drop their hands and move slightly closer together. The participants in the
shell never lower their hands as gravity is always in effect.
The slight decrease in the size of the core makes it hot and dense enough to start fusing
helium. The participants in the core raise their hands once more as energy
is again being generated at the center of the star. Participants in the
shell take a step outward to represent the surge in energy, making the star larger than
it was during the main sequence phase. The star has become a red giant.
Finally, the core of the star runs out of helium to
fuse. When this happens, the participants in the core once again drop their
hands and move slightly closer together. This time the decreasing core
size only raises the temperature enough to allow one last burst of energy,
and push from the core. This causes the shell to drift away into space
while the participants in the core move even closer together.
At this stage the participants in the center represent a white dwarf while the
shell has drifted off to become a planetary nebula. Eventually the material
that once formed the shell of the star will be available to be used in the formation
of another star.
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