0522 GMT October 22, 2019
James Peebles, Michel Mayor and Didier Queloz were announced as this year's winners at a ceremony in Stockholm, BBC reported.
They were jointly awarded the prize for work on the evolution of the Universe and the discovery of a distant planet around a Sun-like star in 1995.
The winners will share the prize money of nine million kronor (£738,000).
James Peebles, of Princeton University in New Jersey, was honored for his contributions to the understanding of the evolution of the Universe and Earth's place in the cosmos.
With others, he predicted the existence of cosmic microwave background radiation, the so-called afterglow of the Big Bang.
He also made major contributions to the theory of dark matter and dark energy, the mysterious components which together make up some 95 percent of the Universe.
Asked what he considered his most important contribution, he said he was "hard-pressed to say", adding that his work had been collaborative.
"It's a life's work," he told the news conference in Stockholm, Sweden.
Michel Mayor and Didier Queloz were awarded the prize for finding 51 Pegasi b, a gas giant orbiting a star 50 light-years away.
It was the first exoplanet discovered around a main-sequence star — ones that fuse hydrogen atoms to form helium atoms in their cores. These are the most numerous kind of star in the Universe, and include our own Sun.
Michael Moloney, chief executive officer of the American Institute of Physics, said, "Their groundbreaking work on discovering the fundamental nature of the Universe and new worlds in distant solar systems has opened up whole new areas of research in cosmology and exoplanet science.
"The discovery of a planet orbiting a star outside our own system has changed our perceptions of our place in the Universe - a Universe that still holds many mysteries to solve."