Jay M. Pasachoff, an astronomer at Williams College who spent more than 50 years traveling the world to observe solar eclipses and, with 74 sightings, probably witnessed more of them than any other human in history, died on Nov. 20 at his home in Williamstown, MA. He was 70.

He was more than just an eclipse fan. He studied the corona, the outermost layer of the sun’s atmosphere, which, being one-millionth as bright as the sun itself, is best studied when the rest of the sun is obscured by the moons — during an eclipse. A focus of his work was testing theories about the corona.

While his contributions to astronomy were many, Dr. Pasachoff was equally adept at encouraging amateurs to share his passion for the night sky.

He and his wife, Naomi, are immortalized in the names of a pair of asteroids: 5100 Pasachoff and 68109 Naomipasachoff.