David James Tholen is an American astronomer at the Institute for Astronomy of the University of Hawaii, who specializes in planetary and solar system astronomy. Tholen has discovered a number of asteroids, including the lost , which may be an Apohele asteroid, and , which certainly is; in fact, it has the smallest semimajor axis and aphelion distance among the known asteroids. He won the H. C. Urey Prize in 1990.
In 1995, Tholen obtained images of the newly-discovered comet Hale-Bopp at a time when the comet was moving very slowly with respect to the background stars, thus permitting the red- green- and blue-filtered images to be combined into a color composite without the background stars appearing as separately colored dots. This color composite image was made publicly accessible via the Institute of Astronomy's web site.
Later, Olivier Hainaut discovered that this image was nearly identical to the one being discussed by late-night radio host Art Bell and one of his guests, Courtney Brown, who claimed that the image proved the existence of an unnatural object following the comet, something supposedly seen by those who had learned how to engage in the technique of "remote viewing". The image provided to Bell by Brown, and eventually made public on Bell's web site, did indeed show an object next to the comet that did not appear in archival images of the sky. In reality, the original image obtained by Tholen had been digitally altered, presumably by taking the image of a star near the edge of the frame, adding it to image next to the comet, and then trimming away the outer edges of the frame.
Tholen and Hainaut exposed the fraud by producing the original image, which showed no such additional object. Nevertheless, some people maintained that Brown's version was the original image and that Tholen had removed the additional object from the one on the Institute's web site. Indeed, the Heaven's Gate cult was so convinced that the additional object was a spaceship coming to take them away from Earth that they committed mass suicide.
David Tholen and Roy Tucker, co-discovers of 2004 MN4, are both fans of the TV series Stargate SG-1, which influenced the naming of the asteroid. The show's most persistent villain is Apophis, an alien also named for the Egyptian god. "We considered a number of names, but 'Apophis' kept floating to the top," says Tucker. "Apophis was a very fitting name for 2004 MN4 not only because of its threatening nature, but also because of its evolution from an Aten asteroid to an Apollo asteroid during the 2029 encounter." .
Tholen is a fan of the University of Kansas Jayhawks college basketball team and the Kansas City Royals Major League Baseball team.
He also plays bass clarinet for the Honolulu Community Concert Band.
He is also an avid user and advocate of the OS/2 operating system.