Daniel Kirkwood, an American Astronomer, born September 27, 1814 in Harford County, Maryland, lived a humble and simple life. His journey towards academic excellence started at the very young age of nineteen, when he first ventured the life of teaching at a country school at Hopewell, York County, Pennsylvania. One of his pupils was keen to learn Algebra, something described by the young Daniel Kirkwood as something that uses the letters of the alphabets instead of figures. With a used textbook copy of Bonnycastle?s Algebra secured from a neighbour, both teacher and student explored to understand the subject, and later on for Daniel Kirkwood, conquered it.
The following year, 1834, Kirkwood enrolled himself at the York County of Academy, at York Pennsylvania, majoring in Mathematics. After four years of mastering his major, he graduated and was immediately appointed first assistant and instructor in mathematics. He held this position for five years, until 1843, until he became Principal of the Lancaster Pennsylvania High School, and it was here in the year 1845 that he married his wife, Sarah A. McNair of Newton, Pennsylvania. And after another five years in Lancaster Pennsylvania, he moved to the Pottsville Academy in Pottsville, Pennsylvania, to become the Principal.
His teaching years extended for three decades more, in the year 1851, he became Professor of Mathematics in Delaware College, and again in Indiana University in Bloomington, Indiana, where he remained until he retired in 1886, with the exemption of years 1865-1867, where he shared his knowledge in Mathematics at Jefferson College in Canonsburg, Pennsylvania. At the age of seventy-seven, he moved to Riverside, California together with his wife, Sarah A. McNair. In Stanford University, he was named non-resident lecturer of Astronomy. Here, he was very popular to his pupils, with them citing him to be an inspiration for them to broaden their interest in the matter learning in general, and not only the love of mathematics. Although he was considered a devout Presbyterian, this never caused any conflict in his studies.
His works in mathematics appeared early on in his learning years. His first noted publication appeared in the year 1848, which consisted of demonstrations ?that the square of the number of rotations per orbital revolution of a planet is proportional to the cube of the radius of the sphere of attraction given by the Laplace nebular hypothesis?. His other known works, like the ?Kepler-type? law and the nebular hypothesis has shown to need several amendments.
Many of his works have been used in today?s scientific literature to verify and slightly modify the Nebular Hypothesis. But perhaps his most important work, the ?gaps? or ?chasms? in the distribution of the mean distances of the asteroids from the sun, was discovered as early as 1857, when on fifty asteroids were known. All in all, he wrote 129 publications, including three books, two of which are his books entitled Meteoric Astronomy (1867) and Comets and Meteors (1873). In his honor, Indiana University named their observatory after him, the Kirkwood Observatory. Kirkwood died in Riverside, California on June 11, 1895. He was buried alongside his wife and daughter in Rose Hill Cemetery, Bloomington, Indiana.