Jan H. Oort, 92; Preeminent Astronomer

Jan H. Oort, who confirmed the theory of galactic rotation and discovered the origin of comets, has died in his homeland, it was reported Thursday.

The Associated Press, quoting fellow astronomer Paul Wesselius, said Oort, perhaps the 20th Century’s preeminent astronomer and whose influence has been compared to that of Copernicus, had died Nov. 5 in Leiden.

He was 92, and the news of his death evidently was delayed until funeral and memorial services were held this week.

Wesselius said he had died of complications of a broken hip suffered in a fall.

“I think it’s fair to say he was the most important living astronomer. Almost no one achieved so much in so many areas of astronomy,” said Wesselius, a professor at the University of Groningen.

Oort not only established a historic reputation for himself as a universal explorer but as director of the University of Leiden’s observatory he was credited with inspiring Dutch influence in astronomy. For a country its size, the Netherlands has a disproportionate number of outstanding astronomers.

“He was the father of Dutch astronomy,” said Dr. Tyeerd Van Albada, another Groningen astronomer. “We all have our jobs thanks to him.”

Among significant contributions, Oort found that the Milky Way rotates around its axis and that our solar system is not at the galaxy’s core but thousands of light-years from it.

The find is widely seen as comparable to Copernicus’ discovery in the 16th Century that the Earth revolves around the sun.

Oort’s other pioneering work on galactic structure showed that the universe was composed of far more matter than previously believed.

He discovered “hidden mass,” dark matter that can’t be seen through conventional telescopes but is now believed to make up more than 90% of the cosmos.

Later, Oort became intrigued by comets and in the 1950s theorized the existence of what has become known as “Oort’s Cloud,” a cluster of space rocks located about a light year outside the solar system and recognized by many astronomers as the most probable source of all comets.

Thanks partly to Oort, the Netherlands has become a leader in radio-astronomical research. One of the world’s largest arrays of dishes is at the northern Westerbork radio-telescopic center.

Oort was born in 1900 in the small northern town of Franeker and graduated from the University of Groningen in 1926.

He spent two years at Yale University.

He was appointed astronomy professor at the University of Leiden in 1935 and stayed there for the rest of his career.

He held honorary degrees from 10 universities, including Harvard, Cambridge and Oxford, and was a member of the Royal Society.

A funeral ceremony attended by about 300 friends, relatives and former students was held Tuesday in Leiden.

Oort is survived by his wife, Mieke, two sons and a daughter.