Dave Jewitt: Beyond Neptune

Early in his career, Dave Jewitt wondered why the outer solar system was so empty. Or was it? Could distant objects exist but simply be too faint for detection?

Beginning in the 1980s, Jewitt and MIT graduate student Jane Luu began searching beyond Saturn. The process involved taking several pictures of the same star field 20 minutes apart, and then looking for slow-moving dots of light against the fixed background of stars. Using a computer that allowed them to “blink” back and forth between the pictures, a moving object would appear to “jump” as the computer blinked. Since objects farther from the Sun move slower than those nearby, Jewitt and Luu named their project the Slow-Moving Object (SMO) survey.

By comparing hundreds of images of the sky, David Jewitt and Jane Luu found dozens of Kuiper Belt Objets such as QB1 shown in the picture. This led to the realization that Pluto itself was a Kuiper Belt Object

In August 1992 at the UH 88-inch telescope, they found their first faint dot, 1992QB1. It turned out to be four times further away than Saturn, far beyond Neptune, in a region now called the Kuiper Belt. From its brightness and distance, they calculated it about 250 km wide. In 1993, they found another and, soon after, dozens more.

Even more thrilling was their calculated prediction that the SMO survey of the whole sky in the plane of the solar system would reveal thousands more.

These calculations proved to be correct and now we know that Pluto is a member of a new class of bodies in the Solar System called Kuiper Belt Objects. This recognition led to a proposal that Pluto be defined as a “dwarf planet” and is distinguished from the other planets such as Earth or Jupiter by being a large member of the Kuiper Belt.

In 2012, Jewitt and Luu were awarded the Kavli Prize in astrophysics and the Shaw Prize in astronomy for their discoveries. By 2017, nearly 2000 objects are known to orbit in the Kuiper Belt, ancient, icy miniature worlds thought to be almost unchanged since the formation of the Solar System.

“The Kuiper Belt has revolutionized our understanding of the solar system. Not only does it answer a long-standing question about where comets come from, but the structure of the Belt has given us a new picture of solar system formation and evolution.”  — Dave Jewitt