Variable stars are stars that change measurably in brightness.
When you see stars in the night sky, they may seem to be the
same night after night. But if you watch them closely, and over
time, you'll see they may change quite a bit. In fact, at some
level almost all stars are "variable". Even our Sun is a
variable star! This is a big web site with a lot of stuff. The
AAVSO has been monitoring variable stars since 1911 and has data
dating back to the 1800's. Right now the AAVSO has about 1,400
members and observers from 52 countries contributing over a
million observations per year. In short, we have a lot going on
and that leads to a pretty big web site. There are hundreds of
thousands of variable stars observable from Earth. To properly
study a star, one needs to follow it over a period of time.
Astronomers simply don't have the resources to monitor them all.
This is where you come in. Observing a variable star is
relatively simple. You basically compare the brightness of the
variable star with that of near