Kuiper Belt Discovery (1993): Jewitt, Luu and 1992 QB1

David Jewitt and Jane Luu discovered the first Kuiper belt object, 1992 QB1, on 30 August 1992, after a five-year search from Mauna Kea. Reported in 1993, it was the first body found beyond Neptune since Pluto and Charon, and it opened a new zone of the Solar System.

What was known before 1993?

The outer Solar System looked strangely empty. Closer to the Sun there are huge numbers of asteroids and short-period comets, but beyond Neptune astronomers knew only Pluto and its moon Charon. Two explanations competed. Perhaps orbits out there are short-lived, cleared out by the gravity of the giant planets. Or perhaps distant objects exist but are so faint that nobody had seen them. Theorists had long proposed a belt of icy bodies beyond Neptune, the Kuiper belt, as a possible source of short-period comets. Nobody had found a member.

What the paper found

• A new object beyond Neptune. 1992 QB1 moves on an orbit outside Neptune’s.
• The first such find since Pluto. It was the first object found beyond Neptune since Pluto and Charon.
• The right kind of orbit. Its distant, near-circular orbit matched the long-hypothesized Kuiper belt.
• A careful claim. The paper’s title calls it a “candidate” Kuiper belt object, and the authors suggested it may be the first detected member of that population.

How they did it

Jewitt and Luu used the University of Hawaii 2.2-meter telescope on Mauna Kea. The method is simple to state and hard to do. Take repeated images of the same patch of sky, then look for faint points of light that shift slowly against the background stars. An object far beyond Neptune moves very little from night to night and is extremely faint, so the search needs dark skies, a sensitive detector and patience. Theirs took five years before it paid off.

Why it mattered

The discovery revealed a third zone of the Solar System beyond the rocky and giant planets. It also changed Pluto’s status: from an oddity at the edge to the largest known member of a whole population. That shift led directly to Pluto’s reclassification as a dwarf planet in 2006. It also gave a new purpose to NASA’s New Horizons flyby of Pluto, whose extended mission went on to explore the Kuiper belt.

Objects on orbits like this one are now called “cubewanos,” a name built from the letters QB1. The object itself was later named 15760 Albion.

What we know now

Thousands of trans-Neptunian objects, bodies that orbit beyond Neptune, are now known. Their orbits carry clues about the Solar System’s history, and some of the most distant ones line up in a way that led Batygin and Brown to propose a still-undetected Planet Nine in 2016.

The pace of discovery is about to jump. During about a month and a half of early test surveys, before its 10-year survey began in mid-2026, the Vera C. Rubin Observatory found 380 new trans-Neptunian objects. Jewitt and Luu needed five years to find the first.

Who wrote it

David Jewitt and Jane Luu worked together on the search at the University of Hawaii telescope. In 2012 Jewitt, Luu and Michael Brown shared the Kavli Prize in Astrophysics for discovering and characterizing the Kuiper belt. Semantic Scholar lists about 427 citations for the paper (October 2026).

Read the original

Jewitt, D. and Luu, J. (1993). “Discovery of the candidate Kuiper belt object 1992 QB1.” Nature 362, 730-732. doi:10.1038/362730a0

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