When researchers discover a
Kuiper belt object, they usually can't determine how big it is, only how bright.
Some astronomers had calculated that another
Kuiper belt object, now known as Ixion (SN: 7/21/01, p.
Stern proposes that the moons and the
Kuiper belt objects they orbit reflect nearly four times more sunlight than typically estimated.
But not one
Kuiper Belt object (KBO) yielded up its size this way until last October 9th.
Last year, Alan Fitzsimmons of Queen's University of Belfast, Northern Ireland, and his colleagues used the Hubble Space Telescope to take images of the
Kuiper belt object 1994TB, which currently lies some 30 times farther from the sun than Earth does.
Marsden of the Harvard-Smithsonian Center for Astrophysics says that "this may be the best determination" of the rotation of a
Kuiper Belt object to date.
The evidence for the paucity of small
Kuiper Belt objects (KBOs) comes from New Horizons imaging that revealed a dearth of small craters on Pluto's largest satellite, Charon, indicating that impactors from 300 feet to 1 mile (91 meters to 1.6 km) in diameter must also be rare.
At such a distance, the sun provides barely a glint of light, yet its influence is still felt -- Ultima Thule is among a group of
Kuiper Belt objects that orbit the distant star in almost a perfect circle, instead of an ellipse like most planetary objects.