Don Machholz and Brian Marsden at the giant binoculars
Don Machholz (right) showed his large comet-hunting binoculars to Brian Marsden (left) during a visit in the 1990s.
Photo supplied courtesy of D. W. E. Green (Central Bureau for Astronomical Telegrams)

One of America’s premier comet hunters, Donald Machholz, died on August 9th.  According to his wife, Michele, he passed away unexpectedly and swiftly from COVID-19 early that morning.   

Born in 1952 in Portsmouth, Virginia, Don became interested in astronomy at age 8. At age 13, he started exploring the sky with his first telescope: a modest 2-inch refractor.  

Then, on New Year’s Day of 1975, he kicked off a personal comet-hunting project, And after 1,700 hours of searching, he found his first comet on September 12, 1978. His second find took another 1,742 hours. Eventually, he spent nearly 9,000 hours comet hunting, during which he discovered a total of 12 comets that bear his name. He became the leading visual comet discoverer in the U.S.

Don took in the sky from a variety of different instruments – some homemade. He swept up Comet C/1985 K1 using a homemade cardboard telescope with a wide-angle, 10-inch scope, which provided a more expansive field of view than most commercial telescopes. His 1986 discovery of Comet 96P/Machholz was made using a “giant” pair of homemade 29 x 130 binoculars. And in 2004 he spotted his tenth comet – C/2004 Q2 – through the 30x eyepiece of his 6-inch f/8 Criterion Dynascope Newtonian reflector. This vintage telescope was a mainstay among amateur astronomers during the 1960s and 70s, and Don had purchased his back in 1968. His final discovery – C/2018 V1 – came in November 2018.

All of Don’s comet discoveries were made from California, but a few years ago, he and his wife relocated to the high desert of Arizona, north of the town of Wikieup (pop. 130).  Here, from his “Stargazers Ranch,” at an altitude of 4,800 feet, he had access to clear and dark (Bortle 2) night skies.

Don Machholz and Joe Rao
Don Machholz (left) welcomed the author (right) to his Arizona ranch in May.

Back in the spring, aware of my interest in observing a possible outburst of the Tau Herculid meteor shower, Don extended an invitation to me and my wife, Renate, to join him and Michele at their ranch. While we didn't see as many meteors as we would have liked, the four of us still had a grand time under a dark Arizona sky.

He was a soft-spoken man and I was amazed at his encyclopedic knowledge of the smallest bodies of the solar system, including meteors, asteroids, and especially comets. I was honored to observe the predawn sky one morning using his big binoculars while he quietly scanned the sky with a 10-inch scope looking for comets, all while soft instrumental music played in the background.

During the day, Don was so very happy to show off all of his optical equipment, and as he took me on a stroll through the huge garage which housed his scopes, he pointed proudly to each one: “I discovered six comets with the Dob . . . I found 96P with the big binos . . .”

Besides comet-hunting, Don was also one of the inventors of the Messier Marathon, a race to observe all the galaxies, nebulae, and clusters in the Messier catalog in a single night around the time of March’s new Moon. He completed the marathon himself 50 times in his life, and he authored a book on the subject: The Observing Guide to the Messier Marathon: A Handbook and Atlas. He also wrote two books on comets: Decade of Comets: A Study of the 33 Comets Discovered by Amateur Astronomers Between 1975 and 1984 and An Observer's Guide to Comet Hale-Bopp.

More recently, Don had begun writing a column for the online news service, EarthSky, and was producing an astronomy podcast, “Looking up with Don Machholz”.

Don is survived by his wife, Michele, and their two sons.

Upon hearing of his passing, many fellow comet observers celebrated Don’s life:

“He was giant in cometary circles, wrote Chris Wyatt, a founding member of the International Comet Quarterly Facebook page, adding, “He has left a legacy for us comet observers and hunters around the world.”

German comet photographer Michael Jäger said: “Don Machholz influenced my life with his comet discoveries. I have spent many nights with his comets. We will always remember him. He was a great comet observer and discoverer.” 

Lastly, a word from noted comet observer, John Bortle, who from 1977 through 1994 wrote Sky & Telescope’s monthly Comet Digest column: “He was one of the last of a rapidly vanishing breed, a visual comet hunter who was successful. I recall a time when visual discovery by amateurs came at a steady rate of 6-8 per year, but no more. Not simply as a fellow comet hunter, but Don was a truly kind human being. His ilk will not come again soon.”




Image of Ernie Ostuno

Ernie Ostuno

August 13, 2022 at 1:21 am

His name is familiar to all amateur astronomers of the last 40 years and he will remain immortal for as long as his comets continue to make their circuits around the sun. Wow, the RV6 Criterion Dynascope...I know exactly what the field of view looks like in the 30x eyepiece. Got mine in 1976 and still use it.

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Tom Hoffelder

August 14, 2022 at 8:26 pm

This is too sad; I have known Don since the very earliest days of the Messier Marathon. RIP my astro friend; I'll see you in the stars.

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Dana Patchick

August 20, 2022 at 3:02 am

A correction to the remark about 'all of Don's discoveries were made from Southern California.' His first comet find in 1978 was made near San Jose, in Northern California, where Don lived at the time. His second comet was found while participating at the RTMC conference in 1985, which was in Southern California.
All the rest were found in Northern California - at Colfax, the small town he lived in up until the recent move to the high desert of Arizona. We'll miss you, Don!

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Monica Young

August 21, 2022 at 2:10 pm

Quite right, we've corrected the sentence to note that his comet discoveries were made from California.

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