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  • Writer's pictureDale DeBakcsy

Jane Luu and the Discovery of the Kuiper Belt.

For a half century after the discovery of Pluto in 1930, the common wisdom was that it was the last, furthest member of our solar system, and that beyond lay only darkness and dust. Though Gerard Kuiper had hypothesised in 1951 that there should be a rich band of asteroid-like objects at the edge of our cosmic neighborhood, over the subsequent decades all attempts to find anything out in the Trans-Plutonic realm yielded nothing. The pessimism about the existence of the Kuiper Belt had become so omnipresent by the 1980s that, when Jane Luu (b. 1963) and David Jewitt (b. 1958) requested time on telescopes sufficiently sophisticated to potentially find objects beyond the known solar system, they were often turned down, as the venture seemed to some in the astronomical community a waste of valuable and rare telescope time.

These setbacks, however, did not deter Luu. Indeed, as adversity goes, academic refusal of observational hours hardly compared to the hardships Luu had already endured. She was born in Saigon in 1963, in a Vietnam entering its second decade of armed conflict, and for the first twelve years of her life war was a constant companion. Her father was an interpreter for the United States armed forces who put his often insubstantial pay in the service of educating his daughter and two sons. When Saigon fell on April 30, 1975, he knew that his years of aiding the United States would be held against him and his family, and told his children to pack one bag each of only absolute essentials, for they would be leaving the next day. Luu did as she was told, though she did manage to sneak her favourite set of coloured pencils into her bag.

The family made it to the United States, but at first found it hard going. Upon arrival, the family was shuffled between refugee camps and motel rooms until Luu’s father left to find work in California while she and her siblings remained behind in scenic Paducah, Kentucky, a sleepy town of some 31,000 souls at the time which has since contracted to a smidge over 27,000 where the biggest employers are the local hospital and WalMart. By 1976, the whole family had reunited in Ventura, California, where Luu quickly added English to the French and Vietnamese she already knew and emerged the valedictorian of her high school in 1980, with a scholarship in hand to help defray the expenses of attending her college of choice, Stanford University. At Stanford, she majored in physics, but in between her undergraduate and graduate years she happened to pick up a job at Pasadena’s Jet Propulsion Laboratories, where everyday she passed photos of the solar system taken by the Voyager missions that JPL had had such a prominent hand in directing. The work being done at JPL inspired her to study the remaining mysteries of the solar system, and by 1986 she was attending graduate school at MIT’s Department of Earth, Atmospheric, and Planetary Science, where her advisor was David Jewitt.

Photo by Paul Valleli

Together, Luu and Jewitt began scanning out past Neptune and Pluto beginning in 1987, and for five long years had nothing to show for it. They were, however, persistent, and had faith that new developments in digital CCD technology would allow them to finally capture glimpses of the faint Trans Neptunic objects, if any were there to be found. When Jewitt left MIT in 1988 to take up a post at Manoa’s University of Hawaii, Luu followed him in due course to continue their working partnership, only leaving in 1990 to pick up a postdoctoral fellowship in Cambridge’s Center for Astrophysics. She continued her work with Jewitt, however, and on August 30, 1992, on the second night of using a new, more sensitive CCD camera setup, the pair found evidence of an object, known officially as 1992 QB1, but nicknamed ‘Smiley’ by Jewitt and Luu in reference to the George Smiley character of John Le Carre’s spy novels. Smiley was an object about one eighth the size of Pluto, located at 44 AUs from the sun (Pluto lies an average distance of 40 AUs from the sun, though it can get as far out as 49).

At that point, the race was on to show that Smiley wasn’t just a loner fluke, but a member of a large family which might be the key to a number of standing mysteries in our cosmic neighborhood. Over the next twenty years, Luu and Jewitt would find a number of such objects, with the total standing as of this writing at 37 minor planets. The existence of the Kuiper Belt provided an explanation for short-period comets, i.e. comets with an orbital period that can be measured in a few dozen years. These objects likely originated in the Kuiper belt, when contact with Neptune’s gravitational field gave them a jolt that sent them streaming as comets towards the sun. For their work on discovering the first inhabitants of the Kuiper Belt, Luu and Jewitt were awarded both the Shaw Prize and the Kavli Prize in 2012.

Since 1992, astronomers have found the Kuiper Belt to be a rich preserve of astronomical objects of many varieties, including the dwarf planets Sedna (discovered 2004) and Eris (discovered 2005), and the planetoid FarFarOut (discovered 2018) which currently holds the record for the farthest known object in our solar system from the Sun (at a distance of 132 AUs, or roughly three times further away than Smiley). From the relatively staid and known solar system which they had inherited, Luu and Jewitt gave us a whole new realm of possibility to explore, where astrophysicists and planetary astronomers have let their brilliance run wild, proposing new worlds from the gravitational clues that lie on beyond Neptune with Golden Age science fiction names like Planet X and Planet Nine. In one day, our little corner of the universe got a lot more interesting, and a lot more fun, and we owe a good deal of that to an immigrant and war refugee who never stopped following wherever her curiosity might lead.


If you'd like to read more about women astronomers like this one, check out my History of Women in Astronomy and Space Exploration, which you can order from Amazon, or from Pen and Sword US or UK.


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