Quaoar and the Edge of the Solar System

PASADENA, Calif. – Since the invention of the telescope, the known edge of our solar system has slowly receded, first with the discovery of Uranus, then Neptune, and finally Pluto.

But in the past decade, astronomers have realized that even Pluto is not the true edge of the solar system; it is merely a member of a vast swarm of icy, planet-shaped objects called planetesimals that orbit in a region known as the Kuiper Belt.

On Wednesday, May 21, Michael E. Brown, an associate professor of planetary astronomy at the California Institute of Technology, will address a number of provocative questions raised by this realization in his talk, "Quaoar and the Edge of the Solar System," one of the ongoing Earnest C. Watson Lecture Series that take place on the Caltech campus. These questions include: What makes a body a planet? Where is the true edge of the solar system? What lies in the uncharted regions beyond the known solar system? Brown will address such questions and provide a glimpse into the most recent research into the exploration of the outer solar system.

Last June, Brown and postdoctoral researcher Chad Trujillo discovered a spherical body orbiting the outer edge of our solar system that was almost as big as Pluto itself. They named it Quaoar, (pronounced KWAH-o-ar) after the creation force of the Tongva tribe, who were the original inhabitants of the Los Angeles basin.

Quaoar provided further proof that Pluto is not the true edge of the solar system, but merely one of many objects that orbit within the Kuiper belt, which is located some four billion miles from Earth. This is the area where comets originate and also where planetary scientists have long expected to eventually find larger planet-shaped objects like Quaoar, which is the largest object found so far in that search.

For over 81 years Caltech has offered the Watson Lecture Series, ever since it was conceived by the late Caltech physicist Earnest Watson as a way to explain science to the local community. The lecture will take place at 8 p.m. in Beckman Auditorium, which is located near Michigan Avenue south of Del Mar Boulevard, on Caltech's campus in Pasadena. Seating is available on a free, no-ticket-required, first-come, first-served basis, beginning at 7:30 p.m. Parking is available in the lots south of Del Mar Boulevard between Wilson and Chester avenues, and in the parking structures at 341 and 405 South Wilson and 370 South Holliston Avenue.