Donald Edward Machholz, Jr., known as the most prolific visual comet discoverer in America over the last century, passed away in the early morning of August 9, 2022, at his home on Stargazer Ranch in Wikieup, Arizona.
Don Machholz was born in Portsmouth, Virginia, on October 7, 1952, to Donald Edward Machholz, Sr., and Doris Louise (Mueller) Machholz. He established an interest in astronomy at the early age of 8 and had his first telescope, a 2-inch refractor, by thirteen. He entered the United States Army in 1971, working as a meteorological observer during the day and continued viewing astronomical objects by night. By mid-1970, he developed a mapping system that assisted him with comet hunting, and after 1700 hours of searching, he visually discovered his first comet on September 12, 1978. Machholz, credited with the visual discovery of 12 comets that bear his name, spent more than 9,000 hours comet-hunting in a career spanning over 50 years. Most of his dozen comets have very long periods orbiting the sun, but two of them are short-period comets that return to the inner solar system every several years (comets 96P/Machholz, found in 1986 with 29×130 binoculars and 141P/Machholz). His most recent named comet was found in 2018. Amongst visual comet discoverers of the past century in the world, only one surpassed Machholz (that being Bill Bradfield of Australia, with 17 named comets), and only one other had as many as Machholz (Minoru Honda of Japan, also with 12). In all of American history, only two comet discoverers found more comets visually than Machholz did — Louis Swift with 13 and Edward Barnard with 14 (both in the 19th century).
Machholz was the author of several astronomy books, including “A Decade of Comets” (1985), a study of the visual comet discoveries between 1975 and 1984; “An Observer’s Guide to Comet Hale-Bopp” (1996); and “The Observing Guide to the Messier Marathon” (2002, Cambridge University Press). Like the 18th-century comet discoverer Charles Messier of Paris, France, who also has twelve named comets, Machholz learned to memorize fuzzy, distant nebulae and galaxies that could be mistaken for comets.
For two decades, Machholz wrote a monthly column on comets in the Journal of the Association of Lunar and Planetary Observers. From 2020 until his death, Machholz wrote and produced a weekly astronomy podcast titled “Looking Up With Don,” in the Top 20 in the Astronomy category on Apple, and he wrote for Earth Sky magazine.
To his astronomical colleagues, both amateur and professional, Machholz was highly respected and known as a legend. His accomplishments were noted by the many journalists who interviewed him over the decades.
Asteroid (245983) Machholz, discovered by Kazimieras Černis, was named in honor of Donald Machholz in November 2017.
To his family, Don was a compassionate, loving, and humorous person who could easily make you laugh. Machholz is preceded in death by his first wife of 33 years, Laura Machholz, and is survived by his second wife of 8 years, Michele Machholz, and their sons, Matthew Machholz, Mark Machholz, and Ansel Cohen.