Thomas Joel Bopp (October 15, 1949 – January 5, 2018) was an American amateur astronomer. In 1995, he discovered comet Hale–Bopp; Alan Hale discovered it independently at almost the same time, and it was thus named after both of them. At the time of the comet discovery he was a manager at a construction materials factory and an amateur astronomer. On the night of July 22, Bopp was observing the sky with friends in the Arizona desert when he made the discovery. It was the first comet he had observed and he was using a borrowed, home-built telescope. The following year his family relocated to Youngstown, Ohio. It was there that, at the age of three, his father Frank Bopp At the age of ten he received his first telescope, a four-inch reflector.
Bopp attended Chaney High School and graduated in 1967. He joined the United States Air Force and served in the Philippines where several times he observed the green flash, an optical phenomenon which occurs just before sunset above the setting sun. who encouraged him to join the Mahoning Valley Astronomical Society (MVAS) in Warren, Ohio. He regularly attended meetings and became friends with astronaut Ronald A. Parise and enjoyed observing deep sky objects with the club's 16" Newtonian reflector telescope. Despite multiple attempts, prior to 1995, Bopp had never observed a comet. On the night of July 22, 1995, eight members of the club met at an undisclosed spot near Vekol Ranch, ninety miles south of Phoenix and as usual Stevens and Bopp were sharing time looking through Stevens's telescope. Stevens had set up his newest home-built telescope Stevens lined up Messier 70 (M70) in the constellation Sagittarius and called Bopp over to look. At around 11 p.m. Bopp looked into the telescope and said, "What's this other object?" Bopp later described what he saw as "a little fuzzy glow" which he initially believed to be a galaxy. On the same night, professional astronomer and experienced comet observer Alan Hale had spotted the same thing at his home in Cloudcroft, New Mexico, while he was killing time waiting for Comet d'Arrest to appear.
The following morning at 8:25 am the office of Brian Marsden, director of the Central Bureau for Astronomical Telegrams, called him back to confirm the sighting was indeed a comet. designating the first comet found during the second half-month of July 1995. Hale's name precedes Bopp's because his was the first report to arrive. It is uncertain who was the first to discover it, as they both spotted it at around the same time. The following day Hale phoned Bopp to introduce himself with the words, "I think that we have something in common." When they met at a conference two months later, Bopp said to the press that he was glad that Hale "turned out to be a nice guy." Bopp has said that "I thought that it would be a comet that would be mentioned in the back of some obscure textbook somewhere, but it's certainly not turned out to be that way." As Hale–Bopp became more visible, Bopp left his job and became a full-time speaker and educator. He enjoyed presenting in schools, science centers and museums, enthusing children with astronomy, and met up with his co-discoverer Hale in Queensland while taking a group of school children to see the 2012 eclipse in Australia.
At White Sands Missile Range in 1997 Bopp was invited to be an observer when an ultraviolet spectrograph was launched by Black Brant rocket to observe the comet and look for argon and neon. Previously unobserved isotopes were discovered in addition to a third sodium tail. Bopp was awarded an honorary doctor of Science degree from Youngstown State University in 1998. Bopp and his father also became the first two members of the Friends of Ward Beecher Planetarium at the university.
In 1997, as comet Hale–Bopp reached its brightest point, Bopp's brother and sister-in-law were killed in a car accident after photographing the comet. "This has been the best week of my life. And the worst," Bopp told a National Geographic reporter.
Bopp and his father Frank have had an asteroid named after them, (7086) Bopp, discovered October 5, 1991, by Carolyn and Gene Shoemaker. In 1997, the Shoemakers, both famous for co-discovering comet Shoemaker–Levy 9, were involved in a car crash. Gene died in the crash, and his ashes were sent to the Moon along with an image of Comet Hale-Bopp, "the last comet that the Shoemakers observed together."
In 1997, when Bopp pointed out the comet would soon disappear from view and would not be visible for another 2380 years, he said he would always continue looking up at the stars.