Two Americans are the winners of the 2006 Nobel Prize for physics.
The Royal Swedish Academy of Sciences announced the award Tuesday in Stockholm.
It honored John Mather and George Smoot for their work exploring the earliest days of the universe, and the origin of galaxies and stars.
Mather and Smoot's analysis of data collected by a U.S. space satellite increased support for the so-called "Big Bang" theory.
That theory says a cosmic explosion billions of years ago formed the universe. Mather is 60 years old and works for the U.S. Goddard Space Flight Center.
The 61-year-old Smoot is a professor at the University of California in Berkeley.
The two scientists will split this year's Nobel prize. It is worth more than one-point-three million dollars.
The Academy's citation credits Mather and Smoot's work on "the blackbody form."
That is the glowing, intensely hot mass of atomic particles believed to have stemmed from the Big Bang.
They also are honored for their analysis of minute temperature changes in cosmic microwave background radiation.
The phenomenon is known as "anisotropy" and it offers an important clue into how the galaxies were formed.
Mather said winning the Nobel Prize does not come as a complete surprise because people have said they should win.
But he said that he and Smoot did not initially understand the importance of their discovery.
The Associated Press quotes the chairman of the Nobel committee for physics Per Carlson, who called Mather and Smoot's work the greatest discovery of the century.
Information for this report is provided by AP, AFP and REUTERS.