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 (Norway)
(February 10, 1998)
You might also be interested in:
Cepheus was a king in Greek mythology. His wife was Cassiopeia and his daughter was Andromeda. Cassiopeia once said some things to make the sea god angry. A monster was sent up to eat Andromeda, but Perseus...more
It depends on which type of motion you are asking about. If you take a birds-eye view from the top of the solar system all the planets orbit around the Sun in a counter-clockwise (or direct) direction....more
Have you ever wondered how astronauts live in space? Did you know they do a lot of the same things we do here on Earth? Astronauts eat, exercise and sleep just like we do. However, their food isn't always...more
There is a really neat internet program called Solar System Live that shows where all of the planets and the Sun are. If you go to that page, you'll see an image similar to the one on the left. Below the...more
The picture of the American Flag (the one put there by the Apollo astronauts) is waving (or straight out) in the wind. How could that be possible if there is no atmosphere on the Moon? Was it some sort...more
I was wondering if there is a new planet? Are there planets (a tenth planet?) after Pluto belonging to our solar system? What are the names of the new planets discovered in the solar system? Are there...more
When an object has a really high energy, it can form a black hole. This is called a primordial black hole. Primordial black holes were formed near the beginning of the universe. Primordial black holes...more