Obituary

Donald Machholz, an American amateur astronomer whose disciplined, decades-long practice of scanning the night sky by eye made him one of the most accomplished visual comet discoverers of the modern era, died in the early morning of August 9, 2022, at his home in Wikieup, Arizona. He was 69.

Over more than five decades, Machholz discovered 12 comets through direct visual observation, devoting upwards of 9,000 hours to systematic comet searching. At a time when automated sky surveys increasingly defined the field, his work stood apart—rooted in patience, method, and the trained perception of the human eye.

Night after night, he swept the sky using binoculars and telescopes, including larger aperture instruments such as his 18-inch Dobsonian, refining a process that depended not on automation but on consistency and attention. His discoveries represent one of the most significant bodies of visual comet work in the modern era, preserving a tradition of observation shaped by individual skill, endurance, and direct engagement with the night sky.

Machholz was born on October 7, 1952, in Portsmouth, Virginia, to Donald Edward Machholz, Sr., and Doris Louise (Mueller) Machholz. He developed an early fascination with astronomy, and by his teenage years had established the disciplined observing routine that would define his life. What began as curiosity became a lifelong structure—one measured not in isolated discoveries but in thousands of hours of deliberate searching.

In 1978, he was one of the independent originators of what became known as the Messier Marathon, an observational challenge to locate all 110 deep-sky objects cataloged by the 18th-century astronomer Charles Messier in a single night. Over the following decades, he completed more than 50 such marathons and wrote extensively on the subject, contributing to a shared culture of observational astronomy.

From 1978 through 2000, he wrote a monthly column, Comet Comments, for astronomy club newsletters and readers worldwide. Between 1988 and 2000, he served as Comets Recorder for the Association of Lunar and Planetary Observers, documenting and contributing to the broader record of comet activity. In later years, he contributed regularly to EarthSky and produced the astronomy podcast Looking Up With Don, continuing to share his knowledge with a wider audience.

In 2014, he married Michele Machholz, an American photojournalist. The couple lived at Stargazer Ranch in northwestern Arizona, where Bortle 2 skies provided ideal conditions for continued observation and where he remained active in comet searching into his later years.

Machholz’s work earned him international recognition and the respect of both amateur and professional astronomers. In 2017, asteroid (245983) Machholz was named in his honor, marking his lasting contribution to the field.

Though technology reshaped astronomy during his lifetime, Machholz’s approach remained constant. His legacy is not only in the comets that bear his name, but in the discipline of looking—of returning, night after night, to the same sky with the expectation that something new might appear.