Who is the history’s greatest explorer? Marco Polo, Magellan, da Gamma and Cook are the main contenders, along—of course—with Christopher Columbus, whose star has fallen over the last few decades. Vancouver, Peary, Amundsen and Scott all have their partisans, as do Lewis and Clark. There are Cortez and de Soto, Stanley and Livingstone, and John Hanning Speke, who discovered the source of the Nile. A strong argument could be made for Jacques Cousteau, or some of the Apollo Astronauts. Let me toss another two new names into the discussion—men who are, improbably, in the prime of their careers: Mike Brown and his former graduate student Chad Trujillo.

Columbus discovered the Americas and Cook, Australia. Mike Brown and a cadre of collaborators, primarily Chad Trujillo and David Rabinowitz, have discovered dozens of planetary bodies beyond the orbit of Pluto, including all six “plutoid” dwarf planets: Quaoar, discovered by Brown and Trujillo, and Sedna, Orcus, Haumea, Makemake and Eris, discovered by Brown, Trujillo and Rabinowitz. Eris is the largest of the six—larger even than Pluto—and was for a time, in popular culture, thought of as the Solar System’s 10th planet.