Headings The Earth
and Beyond Stars Search Questions
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Stars - Life Cycle - Birth - Fusion.
At very high
temperatures, a nuclear
reaction called fusion occurs in stars.
Fusion is the opposite of fission.
A
nuclear reaction changes the
number of protons in the nucleus.
The original element is changed
into a new element (see also radioactivity).
If you are unsure what a proton, element or
nucleus is
go to atoms on the GCSE Chemistry
site.
In
stars, the main fusion
reaction turns hydrogen into
helium.
The nucleus of a hydrogen atom is a positively charged
proton.
When two protons approach
each other
they will repel
each other because they have the same charge.
The protons must be moving very very
fast
if they are to have enough energy to
overcome the force of repulsion.
The two protons can then join
together to form a new
nucleus.
The joining together is called
fusion.
The
new nucleus with two protons is an
atom of helium.
Those of you who are familiar with the
elements
will know that helium has two neutrons as well as two protons.
The real process that turns hydrogen into
helium
is more complicated than that
given above.
The good news is that you don't need to
know the detail for GCSE.
"Hydrogen turns into helium and
gives out energy" is good
enough!
(continued on the next page).
Headings The Earth
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Copyright © 2008 Dr. Colin France. All Rights Reserved.