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), notably the dwarf planet Eris, the only known TNO more massive than Pluto. He has referred to himself as the man who "killed Pluto", because he furthered Pluto being downgraded to a dwarf planet in the aftermath of the 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.