Orbit of 1996 TL66 (10K gif) The breakaway object 1996 TL66 has an orbit much larger than those of other known members of the Kuiper Belt (green/dark blue band) and the outer planets (light blue). Courtesy Jane Luu.

Planetesimal Beyond Neptune - King of the Kuiper Belt

A sizable body discovered in October, 1996, in the Kuiper Belt beyond Neptune has a unique orbit with links to the distant Oort Cloud of comets. Designated 1996 TL66, this object is currently some 5 billion kilometers (35 astronomical units) from the Sun. Assuming it has a dark surface, the new find is rather large and could be up to 500 km (300 miles) in diameter. Discoverers Jane Luu (Harvard University) and her colleagues calculate that 1996 TL66 is now close to the perihelion of a much more eccentric orbit, one with a semimajor axis of 84 AU and a period of nearly 800 years. No other known object bridges the void between the Kuiper Belt and the far more distant Oort Cloud. Whatever its origin, 1996 TL66 undoubtedly represents the first of many such discoveries. Luu's group estimates that thousands more bodies of comparable size and distance await discovery within 30° of the ecliptic plane.

Miniplanet 1996 TL66 (29K jpeg) It might not look like much here, but 21st-magnitude 1996 TL66 (box) is the largest and brightest known member of the Kuiper Belt. These red-light images are 1.6 arcminutes wide; south is up. Courtesy Jane Luu.

This article was part of the web publication of SKY Online on June 6, 1997.