What are Cepheid variables?
"Cepheid variable" is a name for a certain type of star. Both
parts of this name have a special meaning. The "Cepheid" part comes
from the name Cepheus, an ancient Greek king, and one of the
constellations in the northern sky. The first Cepheid variable was
discovered in the constellation Cepheus!
The "variable" part refers
to the changing brightness of the star. If you watched a Cepheid variable star for many hours, you would notice that the
star gets brighter for a while, and then fainter, and then brighter
again... This happens because the surface of the star is
pulsating. The star itself grows larger, then shrinks.
Imagine your lungs as you are breathing. First they fill with air and
expand. Then, as you exhale, they contract. As Cepheid variable stars
expand, they get brighter. When they contract, they get fainter.
Submitted by Henrik Berg (age 20, Norway)
(February 10, 1998)
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