1. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA
2. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, Hawaii 96822, USA
3. Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona 85721, USA
4. W & B Observatory, PO Drawer 1130, Cloudcroft, New Mexico 88317, USA

Correspondence to: Jane Luu¹ Correspondence and requests for materials should be addressed to J.L. (e-mail: Email: luu@cfa.harvard.edu).

Some three dozen objects have now been discovered^{1, 2, 3, 4, 5} beyond the orbit of Neptune and classified as members of the Kuiper belt—a remnant population of icy planetesimals that failed to be incorporated into planets. At still greater distances is believed to lie the Oort cloud—a massive population of cometary objects distributed approximately in a sphere of characteristic dimension 50,000au(ref. 6). Here we report the discovery of an object, 1996TL₆₆, that appears to be representative of a population of scattered bodies located between the Kuiper belt and the Oort cloud. 1996TL₆₆has an orbital semimajor axis of 84au, and is in an extremely eccentric and highly inclined orbit (e = 0.58, i = 24°). With a red magnitude 20.9, it is the brightest trans-neptunian object yet found since Pluto and Charon. Its discovery suggests that the Kuiper belt extends substantially beyond the 30–50auregion sampled by previous surveys, and may contain much more mass than previously suspected.