Is there any other theory to explain the motion of stars in a galaxy?

Dark matter is still hypothetical. There are two possibilities, however. Either dark matter exists and it is real, or there is something wrong with our understanding of how gravity behaves over great distances.

Stars orbit around the centre of galaxies due to centipetal force because there is believed to be a supermassive black hole at the centre of every galaxy. (Note- a black hole isn't actually a hole, it's a star that has died and become so compact that the force of gravity is such that the escape velocity is greater than the speed of light) so stars are held in orbit by the black hole's gravity.

of course not but all theoriesneed observations or experimental fact otsupport or deny

"dark matter" couldhavemany explainations

Dark Energy is much more speculative

or deep space observations are only about 40 years old. distant galaxies were only determined in the 1920s

There is also plasma cosmology: http://www.plasmacosmology.net/

There is a good documentary about the theory here:

http://video.google.com/videoplay?docid=4773590301...

Earth rotates.

answer the damn question