The 2011 Nobel Prize for Physics gas been awarded to three scientists for discovering the accelerating expansion of the universe through observations of exploding stars.

Saul Perlmutter and Adam G. Riess of the U.S. and Brian P. Schmidt of Australia will divide the prize.

They have studied several dozen exploding stars, called supernovae, and discovered that the universe is expanding at an ever-accelerating rate, said the citation from the Nobel Committee for Physics of the Royal Swedish Academy of Sciences.

Perlmutter, from the University of California in Berkeley, has been awarded half of the prize - worth 10 million Swedish krona. The other half will be shared by Schimdt of the Australian National University and Riess of the Johns Hopkins University's Space Telescope Science Institute.

The discovery came as a complete surprise, even to the laureates themselves, the committee added in the statement.