Three scientists will share the 2019 Nobel prize for physics for their work in better understanding the universe.
Swiss scientists Michel Mayor, 77, and Didier Queloz, 53, each from the University of Geneva, were honoured for identifying "an exoplanet orbiting a solar-type star".
The find marks the discovery of the first known planet outside our solar system.
Canadian-American cosmologist James Peebles, 84, of Princeton University, was credited for "theoretical discoveries in physical cosmology".
Mr Peebles, hailed as one of the most influential cosmologists of his time, will collect one half of the 9-million kronor (£745,000) cash award.
The two Swiss scientists will share the other half.
The Nobel committee said Mr Peebles' theoretical framework about the cosmos, and its billions of galaxies and galaxy clusters, amounted to "the foundation of our modern understanding of the universe's history, from the Big Bang to the present day".
His work set the stage for a "transformation" of cosmology over the last half-century, using theoretical tools and calculations that helped interpret traces from the infancy of the universe, the committee said.
Mr Peebles is the Albert Einstein professor of science at Princeton.
Mr Mayor and Mr Queloz were credited with having "started a revolution in astronomy" notably with the discovery of exoplanet 51 Pegasi B, a gaseous ball comparable with Jupiter.
The planet was discovered in 1995 when, as Mr Mayor recalled, "no one knew whether exoplanets existed or not".
An exoplanet is a planet outside our solar system.
Mr Mayor said: "Prestigious astronomers had been searching for them for years, in vain!"
The committee said more than 4,000 exoplanets have been found in the Milky Way since then, and "strange new worlds are still being discovered, with an incredible wealth of sizes, forms and orbits".
The University of Geneva quoted Mr Mayor and Mr Queloz as saying it was "simply extraordinary" that they won the prize for "the most exciting" discovery of their careers.
The cash prize comes with a gold medal and a diploma that are received at a ceremony in Stockholm on 10 December, the anniversary of the death of the prize's founder Alfred Nobel in 1896, together with five other Nobel winners.
The sixth one, the peace prize, is handed out in Oslo, Norway on the same day.
This was the 113th Nobel prize in physics, of which 47 awards have been given to a single laureate.
Only three women have been awarded it so far: Marie Curie in 1903, Maria Goeppert-Mayer in 1963 and Donna Strickland in 2018, according to the Nobel website.
Americans William G Kaelin Jr. and Gregg L. Semenza and Britain's Peter J. Ratcliffe won the Nobel prize for physiology or medicine on Monday.
The Nobel prize for chemistry will be announced Wednesday, two literature prizes will be awarded on Thursday, and the peace prize comes on Friday.
This year will see two literature prizes handed out because the one last year was suspended after a sex scandal rocked the Swedish Academy.