The three winners of the Nobel Prize in Physics 2020 helped prove the existence of black holes, and one is a longtime user of the W.M. Keck Observatory atop Mauna Kea.

U.S. astronomer Andrea Ghez, of the University of California, Los Angeles, has been studying the Galactic Center — the central region of the Milky Way galaxy — at the Keck Observatory on Hawaii island since 1995, according to the observatory’s website.

Ghez shared half of the Nobel Prize with Reinhard Genzel, who represents both UCLA and the Max Planck Institute in Germany, for discovering a supermassive black hole at the center of the Milky Way in the 1990s.

Roger Penrose, of the University of Oxford, received the other half of the Nobel Prize for proving with mathematics in 1964 that the general theory of relativity predicted the formation of black holes.

The Nobel Assembly announced the prize Saturday at the Royal Swedish Academy of Sciences in Stockholm.

Ghez is only the fourth woman to win the Nobel in physics, following Marie Curie in 1903, Maria Goeppert Mayer in 1963 and Donna Strickland in 2018, according to The New York Times.

“I’m so thrilled,” she said in an email to The Times.

Ghez has been working solely on the supermassive black hole during her 20-plus years of doing research at the Keck Observatory.

“For 25 years she’s had one research topic: proving that that black hole at the center of the Milky Way exists,” Hilton Lewis, the observatory’s director, told the Honolulu Star-Advertiser.

Although scientists compete to use the observatory’s telescopes, Lewis said Ghez probably uses them more often than anyone else — about a dozen nights per year.

The observatory’s twin telescopes, each with a 10-meter primary mirror, are among the most powerful telescopes in the world, Lewis said, which is “critical” for the work Ghez does.

Black holes, which exist at the center of every galaxy, fascinate people because “the idea of some monster out there sucking everything up is a pretty weird thing,” Penrose said in an interview with the Associated Press. He said our galaxy and the galaxies near us “will ultimately get swallowed by one utterly huge black hole. This is the fate … but not for an awful long time, so it’s not something to worry too much about.”

They are so massive that nothing, not even light, can escape their gravitational pull. They warp and twist light in a way that seems unreal and cause time to slow and stop.

“Black holes, because they are so hard to understand is what makes them so appealing,” Ghez, 55, said. “I really think of science as a big, giant puzzle.”

While the three scientists showed the existence of black holes, it wasn’t until last year that people could see one for themselves when another science team captured the first and only optical image of one. It looks like a flaming doughnut from hell but is in a galaxy 53 million light-years from Earth.

Penrose, a mathematical physicist who got the call from the Nobel Committee while in the shower, was surprised at his winning because his work is more theoretical than observational, and that’s not usually what wins physics Nobels.

What fascinated Penrose more than the black hole was what was at the other end of it, something called the “singularity.” It’s something science still can’t figure out.

“Singularity, that’s a place where the densities and curvatures go to infinity. You expect the physics go crazy,” he said from his home. “If you fall into a black hole, then you pretty well inevitably get squashed into this singularity at the end. And that’s the end.”

Penrose said he was walking to work with a colleague 56 years ago, thinking about “what it would be like to be in this situation where all this material is collapsing around you.” He realized he had “some strange feeling of elation,” and that was when things started coming together in his mind.

Martin Rees, the British astronomer royal, noted that Penrose triggered a “renaissance” in the study of relativity in the 1960s, and that, together with a young Stephen Hawking, he helped firm up evidence for the Big Bang and black holes.

“Penrose and Hawking are the two individuals who have done more than anyone else since Einstein to deepen our knowledge of gravity,” Rees said. “Sadly, this award was too much delayed to allow Hawking to share the credit.”

Hawking died in 2018, and Nobel Prizes are awarded only to the living.

New York University astrophysicist Glennys Farrar said: “There is no doubt that if this prize were awarded when Hawking was still alive, he would share it. He did overall more significant work on this subject than almost anyone.”

Genzel, 68, and Ghez won because “they showed that black holes are not just theory — they’re real, they’re here, and there’s a monster-size black hole in the center of our galaxy, the Milky Way,” said Brian Greene, a theoretical physicist and mathematician at Columbia University.

In the 1990s, Genzel and Ghez, leading separate groups of astronomers, trained their sights on the dust-covered center of our Milky Way galaxy, a region called Sagittarius A*, where something strange was going on. It was “an extremely heavy, invisible object that pulls on the jumble of stars, causing them to rush around at dizzying speeds,” according to the Nobel Committee.

It was a black hole. Not just an ordinary black hole, but a supermassive one, 4 million times the mass of our sun.

The first image Ghez got was in 1995, using the Keck Telescope in Hawaii that had just gone online. A year later, another image seemed to indicate that the stars near the center of the Milky Way were circling something. A third image led Ghez and Genzel to think they were really on to something.

A fierce competition developed between Ghez and Genzel, whose team was using an array of telescopes at the European Southern Observatory in Chile.

“Their rivalry elevated them to greater scientific heights,” said Harvard astronomer Avi Loeb.

Lewis said Ghez is still observing the black hole with the Keck Observatory’s telescopes.

“Earlier this year, she found some object — somewhere between a cloud of gas and a star — that’s circling around this black hole,” Lewis said. “It shouldn’t be there. It shouldn’t be possible for something like that to exist. So, she picks up all these exotic things that are also in this area.”

The Nobel comes with a gold medal and 10 million kronor (more than $1.1 million), courtesy of a bequest left 124 years ago by the prize’s creator, Alfred Nobel, the inventor of dynamite.