James Elliot, an astronomer who used light from distant stars to study planetary objects throughout the solar system, leading to his discovery of the rings of Uranus, died on March 3 at his home in Wellesley, Massachusetts. He was 67. His daughter Lyn said the cause was complications of cancer treatment.
Dr. Elliot spent his career, mostly at the Massachusetts Institute of Technology, scrutinizing planets by observing how much starlight they blocked. Using phenomena known as stellar occultations, he could observe changes in the brightness of a star when it was hidden by a planet, thus determining the planet’s size and the temperature and pressure of any atmosphere it had.
In 1977, using a telescope in an airplane, Dr. Elliot led a team of Cornell University scientists to observe the planet Uranus when it passed between Earth and a star. Flying at night over a patch of the Indian Ocean where Uranus’s shadow was to be cast, he had the foresight to turn on his equipment more than a half-hour early. This allowed him to record a series of slight dimmings that provided the first evidence of Uranus’s rings.