(308933) 2006 SQ372

Lore & Background

2006 SQ372 was discovered through the Sloan Digital Sky Survey by astronomers Andrew Becker, Andrew Puckett and Jeremy Kubica on images first taken on 27 September 2006, with precovery images dated to 13 September 2005. Its orbit is highly eccentric, crossing that of Neptune near perihelion but bringing it more than 1,500 AU from the Sun at aphelion, taking about 22,500 years to orbit the Solar System's barycenter. The large semi-major axis makes it similar to (87269) 2000 OO67 and Sedna.

The object's orbit currently comes closer to Neptune than any other giant planet. More than half of simulations show it getting too close to either Uranus or Neptune within the next 180 million years, sending it in a currently unknown direction. This makes classification difficult: the Minor Planet Center lists centaurs and scattered disc objects together, and (29981) 1999 TD10 is another such object that blurs the two categories.

Physically, with an absolute magnitude of 8.1, it is estimated to be about 60 to 140 km in diameter. Michael Brown estimates an albedo of 0.08, giving a diameter of around 110 km. The object could possibly be a comet. Its origin is debated: the discoverers hypothesize it could come from the Hills cloud, while Michael Brown considers other possibilities, including that it may have formed from debris just beyond Neptune in the Kuiper belt and been kicked into its distant orbit by a planet like Neptune or Uranus.

Reader's Guide

The significance of (308933) 2006 SQ372 lies in its extreme orbital characteristics and the classification ambiguity it presents. With a barycentric semi-major axis of 796 AU and a period of 22,466 years, it joins a small group of objects like (87269) 2000 OO67 and Sedna that have large semi-major axes. Its orbit is so eccentric that different epochs yield vastly different heliocentric solutions—for example, a 2005 epoch gives an aphelion of 1557 AU, while a 2011 epoch gives 2006 AU—demonstrating the need for barycentric coordinates for stability. The object's future is uncertain: more than half of simulations show it will be perturbed by Uranus or Neptune within 180 million years, sending it in an unknown direction. This dynamical instability, combined with its cometary-like orbit and possible cometary nature, challenges rigid classification between centaurs and scattered disc objects. Its discovery via the Sloan Digital Sky Survey and the ongoing debate over its origin—whether from the Hills cloud or the Kuiper belt—underscore its role in understanding the outer Solar System's structure and evolution.

Did You Know?

• 2006 SQ372 takes about 22,500 years to orbit the barycenter of the Solar System.
• More than half of simulations show it will get too close to Uranus or Neptune within the next 180 million years.
• Its diameter is estimated at approximately 123 kilometers, though Michael Brown's albedo estimate gives around 110 km.