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Daniel Kirkwood

September 26, 2014

Science isn’t just about explaining why things are — it’s also about explaining why things aren’t. Astronomer Daniel Kirkwood, for example, is best known for explaining gaps in the asteroid belt and the rings of Saturn — zones that are clear of the normal debris.

Daniel Kirkwood look toward a dark gap in the rings of SaturnDaniel Kirkwood look toward a dark gap in the rings of SaturnKirkwood was born 200 years ago tomorrow in Maryland. He grew up on a farm, and was educated at a small country school. As a teenager, he became a teacher, and he taught himself algebra. He liked it so much that he studied math in college, and began applying that knowledge to astronomy. In 1856, he joined the faculty of the University of Indiana, where he stayed for 30 years.

Kirkwood didn’t observe the heavens with a telescope. Instead, he used other people’s observations to develop new theories.

As astronomers discovered more and more asteroids in a belt between Mars and Jupiter, for example, Kirkwood noticed that there were gaps — certain distances from the Sun that were bereft of asteroids. He calculated that Jupiter’s gravity would nudge asteroids away from those distances, clearing out the gaps. He also calculated that the gravity of moons of Saturn would do the same thing, clearing out the wide gaps in Saturn’s rings. Today, those types of gaps are named in Kirkwood’s honor.

Kirkwood also came up with the correct explanation for meteor showers — they’re bits of debris from comets. Those discoveries have earned him an honored spot in the history of American astronomy.

Script by Damond Benningfield, Copyright 2014


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