WASHINGTON — Gart Westerhout, a Dutch-born astronomer who gained international renown in the early 1950s when he helped chart the Milky Way galaxy with unprecedented precision, and who later created the astronomy program at the University of Maryland, died Oct. 14 at a senior living community in Catonsville, Md.
He was 85 and had retired in 1993 as scientific director at the US Naval Observatory in northwest Washington.
Dr. Westerhout made the first of his achievements — principally in a field known as radio astronomy — in Holland in the years after World War II. He was among the youngest in a pioneering group of scientists taught and led at the University of Leiden by astronomer Jan Oort, who has been described as a ‘‘modern Copernicus.’’
For centuries, astronomers have been aided by tools such as telescopes. Dr. Westerhout joined the nascent field of radio astronomy and set out to study the heavens using radio waves emitted by stars, galaxies, and other celestial bodies.
He conducted his earliest research on a World War II relic — a large radar antenna left behind by the German military and commandeered by the Dutch scientific community. With his colleagues, and on increasingly sophisticated equipment, Dr. Westerhout tracked radio waves emitted by interstellar hydrogen gas to compile the first detailed map of the spiral structure of the Milky Way.
Astronomers describe that achievement as a major advance in the field. Scientists had long suspected that the Milky Way had the spiral structure of other galaxies, said Bill Howard, a radio astronomer who lives in McLean, Va., and first met Dr. Westerhout in Leiden. But observers were too ‘‘deeply immersed within the dust and gas within in our galaxy,’’ he said, to know for sure.
‘‘For the first time, we could see with some precision that what appears to be a random collection of stars up there is really organized,’’ said Kurt Riegel, who was Dr. Westerhout’s first doctoral student at the University of Maryland and later headed the national astronomy centers at the National Science Foundation. ‘‘The radio observations . . . allowed astronomers to get a handle on our own galaxy.’’
At the time, Dr. Westerhout had not yet turned 30.
His work attracted the attention of scientist John Toll, a future president of the University of Maryland. In 1961, Dr. Westerhout received an invitation from Toll — ‘‘out of the blue,’’ he once recalled — to go to Maryland and create an astronomy program.
Dr. Westerhout arrived in 1962 and built a full-fledged department with undergraduate and graduate programs. ‘‘He basically got the program going,’’ said Stuart Vogel, the department chair. ‘‘He was the one who hired a lot of our astronomers and made us into what we are.’’
‘‘If a person gets a PhD at Maryland,’’ Howard said, ‘‘he is very well educated in the research area to make major contributions to the field.’’
In 1977, Dr. Westerhout left to become scientific director at the US Naval Observatory. Established in 1830, it is one of the oldest scientific institutions in the United States.
The institution is most popularly known for its timekeeping mission, as the home of the nation’s master clock. It is also tasked with following the positions of celestial bodies and the motions of the Earth.
Gart Westerhout was born in The Hague.
He fashioned his first telescope from an eyeglass lens and a magnifying glass.