Michael E. Brown (born June 5, 1965) is an American astronomer, who has been professor of planetary astronomy at the California Institute of Technology (Caltech) since 2003. His team has discovered many trans-Neptunian objects (TNOs), including the dwarf planet Eris, which was originally thought to be bigger than Pluto, triggering a debate on the definition of a planet.
He has been referred to by himself and by others as the man who "killed Pluto", because he furthered Pluto's being downgraded to a dwarf planet in the aftermath of his discovery of Eris and several other probable trans-Neptunian dwarf planets. He is the author of How I Killed Pluto and Why It Had It Coming, published in 2010. He was awarded the Kavli Prize (shared with Jane Luu and David C. Jewitt) in 2012 "for discovering and characterizing the Kuiper Belt and its largest members, work that led to a major advance in the understanding of the history of our planetary system."
Brown was raised in Huntsville, Alabama, and graduated from Virgil I. Grissom High School in 1983. He earned his A.B. in physics from Princeton University in 1987, where he was a member of the Princeton Tower Club. Brown completed his senior thesis, titled "Simulating the measurement of the correlation function of the Shane–Wirtanen galaxy counts", under the supervision of Edward Groth. He did his graduate studies at the University of California, Berkeley, where he earned an M.A. degree in astronomy in 1990 and a Ph.D. degree in astronomy in 1994.
Brown is credited by the Minor Planet Center with the discovery or co-discovery of 29 minor planets, not counting Haumea. He is best known in the scientific community for his surveys for distant objects orbiting the Sun. His team has discovered many trans-Neptunian objects (TNOs). Particularly notable are Eris, a dwarf planet and the only TNO known to be more massive than Pluto, leading directly to Pluto's demotion from planet status; Sedna, a planetoid thought to be the first observed body of the inner Öpik–Oort cloud; and Orcus. Brown's team famously named Eris and its moon Dysnomia with the informal names Xena and Gabrielle, respectively, after the two main characters of Xena: Warrior Princess. Together with Jean-Luc Margot in 2001, he also discovered Romulus and Linus, two minor-planet moons in the asteroid belt.
