It seems impossible, given how instantly recognizable Albert Einstein’s shock of white hair, bushy mustache and lined face remain six decades after his death, but there was a time when he was not famous. In fact, there was a time when the German-born prodigy was not a full-fledged physicist. Instead, he was patent examiner in Bern, Switzerland, who conducted scientific research in his off hours.

In 1905, when he was 26, Einstein began revolutionizing physics with his theory of special relativity, which helped redefine the relationship between space and time. One of the world’s most iconic mathematical equations — E=mc2 — grew out of special relativity.

That work secured Einstein a series of academic positions, but it didn’t make him famous. Neither did his theory of general relativity, which he published in 1915. Einstein argued that what we understand as gravity is, in fact, from the curvature of space and time — a hotly debated notion among physicists at the time.

Then came the solar eclipse of 1919 — more than six minutes of darkness along a path that stretched from South America to Africa and changed the course of Einstein’s life. Some people refer to the May 29, 1919, event “Einstein’s eclipse.”

Nearly a century later, on Aug. 21, a solar eclipse will sweep across the United States in one of the most anticipated astronomical events in the country’s history. It will give scientists an opportunity to study the sun’s volatile corona, the wisps of plasma that billow and sometimes explode around the star.

In 1919, British astronomers, led by Sir Arthur Eddington, used the eclipse to prove that the light from stars was being deflected by the sun’s gravitational field at exactly the degree Einstein’s theory predicted.

Newspapers around the world celebrated the accomplishment.  “Einstein Theory Triumphs,” the New York Times reported on its front page Nov. 10, 1919. “Men of Science More or Less Agog Over Results of Eclipse Observations.”

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What Einstein had done, effectively, was change the conversation about space, and how people understood and related to it. Just as importantly, the scientific breakthrough offered a reprieve from the devastation of World War I, which had claimed the lives of an estimated 17 million people.

“Europe was in mourning,” said Jimena Canales, author of “The Physicist and the Philosopher: Einstein, Bergson, and the Debate That Changed Our Understanding of Time.” “The public was thirsty for news that was not about what was going on around them.”

Einstein won the Nobel Prize in 1921. Afterward, he traveled the world, hobnobbing with royalty and Hollywood stars. Charlie Chaplin invited him to the premiere of his new movie, “City Lights,” in 1931, and reportedly said to him, “They’re cheering us both, you because nobody understands you, and me because everybody understands me.”

Einstein fled Germany in 1933 as the Nazis came to power and began ousting Jewish scientists from the country’s universities. In a speech to a packed audience at London’s Royal Albert Hall on Oct. 3, 1933, Einstein warned of the dangers Hitler posed.

“If we want to resist the powers which threaten to suppress intellectual and individual freedom we must keep clearly before us what is at stake,” he said, “and what we owe to that freedom which our ancestors have won for us after hard struggles.”

He sailed to the United States four days later, eventually taking a position at the Institute for Advanced Study in Princeton, N.J, where his fame grew. He was a pacifist and an outspoken champion of civil rights, joining the NAACP and corresponding with W.E.B. Du Bois, a co-founder of the organization.

“Einstein, in that time, was becoming more than a public scientist,” Canales said. “He became oracular, and he didn’t shy away” from it. “He created this new role [now inhabited] by people like Stephen Hawking and Carl Sagan.”

By the time he died in 1955 at the age of 76, Einstein’s name had become a synonym for genius. And it all began in 1919, after the moon briefly blocked the sun.

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