High Quality Content by WIKIPEDIA articles! Charles Thomas Kowal (November 8, 1940 – November 28, 2011) was an American astronomer known for his observations and discoveries in the Solar System. As a staff astronomer at Caltech`s Mount Wilson and Palomar Mountain observatories between 1961 and 1984, he found the first of a new class of Solar System objects, the centaurs, discovered two moons of the planet Jupiter, and discovered or co-discovered a number of asteroids, comets and supernovae. He was awarded the James Craig Watson Medal for his contributions to astronomy in 1979.