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Fred Whipple

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Fred Lawrence Whipple (1906-2004) was an American astronomer who made significant contributions to the study of comets and meteors. While working at Harvard College Observatory, he proposed in 1950 the 'icy conglomerate' model (popularly known as the 'dirty snowball' theory) suggesting that comet nuclei are composed primarily of frozen water and other ices mixed with dust and rocky material. This theory, which explained how comets form their characteristic tails when approaching the sun, was confirmed in 1986 when the Giotto spacecraft observed Halley's Comet up close. Whipple also discovered six comets and pioneered photographic techniques for tracking meteors.

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Who was Fred Whipple?

Fred Lawrence Whipple was an American astronomer who lived from 1906 to 2004. He studied comets, meteors, and small bodies in the Solar System.

What is Fred Whipple known for?

He proposed the icy conglomerate model of comet nuclei in 1950. The idea became widely known as the dirty snowball theory.

What does the dirty snowball theory say?

It describes a comet nucleus as a mixture of ice and embedded dust or rocky material. As a comet approaches the Sun, heating can release gas and dust to form a coma and tail.

Where did Fred Whipple work?

Whipple worked at the Harvard College Observatory. His research there made him one of the leading American comet specialists of the 20th century.