Astronomers Michael E. Brown, Chad Trujillo, and David L. Rabinowitz discovered the trans-Neptunian object Sedna.

Michael E. "Mike" Brown 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.

Chadwick A. Trujillo is an American astronomer, discoverer of minor planets and the co-discoverer of Eris, the most massive dwarf planet known in the Solar System.

David Lincoln Rabinowitz is an American astronomer, discoverer of minor planets and researcher at Yale University.

A trans-Neptunian object (TNO), also written transneptunian object, is any minor planet in the Solar System that orbits the Sun at a greater average distance than Neptune, which has an orbital semi-major axis of 30.1 astronomical units (AU).

Sedna (minor-planet designation: 90377 Sedna) is a dwarf planet in the outermost reaches of the Solar System, orbiting the Sun far beyond the orbit of Neptune. Discovered in 2003, the frigid planetoid is one of the reddest known among Solar System bodies. Detailed spectroscopic analysis has revealed Sedna's surface to be a mixture of the solid ices of water (H₂O), carbon dioxide (CO₂), and ethane (C₂H₆), along with occasional sedimentary deposits of methane (CH₄)-derived, vividly reddish-colored organic tholins, a surface chemical makeup somewhat similar to those of other trans-Neptunian objects. Sedna has no detectable atmosphere, as its temperature is far too low for solids to volatilize. Within the range of uncertainty, it is tied with the dwarf planet Ceres in the asteroid belt as the largest dwarf planet not known to have a moon. With a diameter of roughly 1,000 km, it is nearly the size of Tethys, a moon of Saturn. Owing to its lack of known moons, the Keplerian laws of planetary motion cannot be utilized for determining its mass, and the actual figure remains as yet unknown.