Daniel Kirkwood | |
|---|---|
 Daniel Kirkwood | |
| Born | (1814-09-27)September 27, 1814 |
| Died | June 11, 1895(1895-06-11) (aged 80) |
| Alma mater | York County Academy,York, PA |
| Known for | Discovery of theKirkwood gaps |
| Scientific career | |
| Fields | astronomy, mathematics |
| Institutions | University of Delaware Indiana University Jefferson College Stanford University |
Daniel Kirkwood (September 27, 1814 – June 11, 1895) was an Americanastronomer.
Kirkwood was born inHarford County, Maryland, to John and Agnes (née Hope) Kirkwood.[1] He graduated in mathematics from the York County Academy inYork, Pennsylvania, in 1838. After teaching there for five years, he became Principal of the Lancaster High School inLancaster, Pennsylvania, and after another five years he moved on to become Principal of the Pottsville Academy inPottsville, Pennsylvania. In 1851, he was elected as a member to theAmerican Philosophical Society.[2] The same year he became Professor of Mathematics atDelaware College and in 1856 Professor of Mathematics atIndiana University inBloomington, Indiana, where he stayed until his retirement in 1886, with the exception of two years, 1865–1867, atJefferson College inCanonsburg, Pennsylvania.
Kirkwood's most significant contribution came from his study ofasteroid orbits. When arranging the then-growing number of discovered asteroids by their distance from the Sun, he noted several gaps,[3] now namedKirkwood gaps in his honor, and associated these gaps withorbital resonances with the orbit ofJupiter. Further, Kirkwood also suggested a similar dynamic was responsible forCassini Division inSaturn's rings, as the result of aresonance with one ofSaturn's moons. In the same paper, he was the first to correctly posit that the material inmeteor showers iscometary debris.
Kirkwood also identified a pattern relating the distances of theplanets to their rotation periods, which was called Kirkwood's Law. This discovery earned Kirkwood an international reputation among astronomers; he was dubbed "the AmericanKepler" bySears Cook Walker, who claimed that Kirkwood's Law proved the widely heldSolar Nebula Theory. The "Law" has since become discredited as new measurements of planetary rotation periods have shown that the pattern doesn't hold.
In 1891, at age 77, he became a lecturer in astronomy atStanford University. He died inRiverside, California, in 1895.
Altogether he wrote 129 publications, including three books. The asteroid1951 AT was named1578 Kirkwood in his honor and so was the lunar impact craterKirkwood, as well as Indiana University'sKirkwood Observatory. He is buried in the Rose Hill Cemetery inBloomington, Indiana, where Kirkwood Avenue is named for him.
Kirkwood was a cousin ofIowa governorSamuel Jordan Kirkwood who becameUnited States Secretary of the Interior under PresidentJames A. Garfield and PresidentChester A. Arthur.[4]
