Fred Lawrence Whipple (November 5, 1906–August 30, 2004) was an American astronomer.

He is best known for writing an influential paper in Astrophysical Journal in 1950 [1] (http://adsabs.harvard.edu//full/seri/ApJ../0111//0000375.000.html), in which he proposed the now-confirmed "dirty snowball" theory of comet composition (although he originally used the term "icy conglomerate").

He joined Harvard College Observatory in 1931 and studied the trajectories of meteors, confirming that they originated within the solar system rather than from interstellar space.

In 1933, he discovered the periodic comet 36P/Whipple and the asteroid 1252 Celestia. He also discovered or co-discovered five other non-periodic comets, the first of which was C/1932 P1 Peltier-Whipple, independently discovered by the famed amateur astronomer Leslie Peltier.

During World War II, he invented a device for cutting tinfoil into chaff to confuse enemy radar tracking Allied aircraft. He was awarded a Certificate of Merit for this in 1948.

He also invented a "meteor bumper" or "Whipple shield", which protects spacecraft from impact by small particles by vaporizing them.

In 1955 he became director of the Smithsonian Astrophysical Observatory (SAO), remaining in this post until 1973.

He anticipated the era of artificial satellites and organized the "Moonwatch" group to track them. His group was the only one prepared and ready to make observations when the Soviet Union unexpectedly launched Sputnik I in 1957.

In 1983 he won the Gold Medal of the Royal Astronomical Society. In 1986 he was awarded the Bruce Medal by the Astronomical Society of the Pacific, and in 1987 he was awarded the Henry Norris Russell Lectureship by the American Astronomical Society.

He was also awarded the Distinguished Federal Civilian Service Award by US President John F. Kennedy in 1963.

Asteroid 1940 Whipple is named after him, as is the Whipple Observatory on Mount Hopkins in Arizona.

Whipple passed away in 2004, aged 97.

Asteroids discovered: 1

1252 Celestia

February 19, 1933

External links

• Bruce Medal entry with picture (http://www.phys-astro.sonoma.edu/BruceMedalists/Whipple)
• Report of his death (BBC) (http://news.bbc.co.uk/1/hi/sci/tech/3614064.stm)
• Report of his death (CNN) (http://www.cnn.com/2004/TECH/space/08/31/obit.whipple.ap/index.html)
• Astronomy.com obituary (http://www.astronomy.com/default.aspx?c=a&id=2429)
• Harvard-Smithsonian Center for Astrophysics press release (http://cfa-www.harvard.edu/press/pr0428.html)

"Dirty Snowball" paper

• Part I: ApJ 111 (1950) 375 (http://adsabs.harvard.edu//full/seri/ApJ../0111//0000375.000.html)
• Part II: ApJ 113 (1951) 464 (http://adsabs.harvard.edu//full/seri/ApJ../0113//0000464.000.html)

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