NASA's Hubble finds Kuiper Belt duo may be trio

 The puzzle of predicting how three gravitationally bound bodies move in space has challenged mathematicians for centuries, and has most recently been popularized in the novel and television show "3 Body Problem." There's no problem, however, with what a team of researchers say is likely a stable trio of icy space rocks in the solar system's Kuiper Belt, found using data from NASA's Hubble Space Telescope and the ground-based W. M. Keck Observatory in Hawaii

"The universe is filled with a range of three-body systems, including the closest stars to Earth, the Alpha Centauri star system, and we're finding that the Kuiper Belt may be no exception," said the study's lead author Maia Nelsen, a physics and astronomy graduate of Brigham Young University in Provo, Utah.

Known since 1992, KBOs are primitive icy remnants from the early solar system found beyond the orbit of Neptune. To date, over 3,000 KBOs have been cataloged, and scientists estimate there could be several hundred thousand more that measure over 10 miles in diameter. The largest KBO is dwarf planet Pluto.

The Hubble finding is crucial support for a KBO formation theory, in which three small rocky bodies would not be the result of collision in a busy Kuiper Belt, but instead form as a trio directly from the gravitational collapse of matter in the disk of material surrounding the newly formed Sun, around 4.5 billion years ago. It's well known that stars form by gravitational collapse of gas, commonly as pairs or triples, but that idea that cosmic objects like those in the Kuiper Belt form in a similar way is still under investigation.