|Announced on IAUC
8577 on 29 Jul 2005 with more details given on MPEC
2005-O41 the same day, this extraordinary object had been
originally detected as a (very slow) moving object on 5th January
2005, from images taken on 21st October 2003 nearly 15 months
It is slightly larger than Pluto and currently over 96 times
further from the Sun than the Earth (or 96 AU) and over three
times further away than Pluto. It is the most distant object
observed in the Solar System to date, even further than the
previous record holder Sedna, discovered by the same team in
November 2003 which is just over 88 AU away.
2003 UB313 is now at about at its furthest from the
Sun, coming closest to the Sun 250 years from now at a distance of
about 38 AU.
The discoverers M. E. Brown, C. A. Trujillo, and D.
Rabinowitz used the Palomar 1.2-m Schmidt telescope and very large
field Quest camera
(172 Megapixels - 112 CCDs(!) arranged to cover 3.6°x4.6° at the
focal plane of this famous instrument) in their ongoing search for
large distant solar system objects. Other large transneptunian
objects discovered by them in the last few years include Sedna,
Quaoar, Orcus and
Brown had intended to announce 2003 UB313 in
September 2005 after completing follow-up observations with other
large instruments including the Spitzer Space Telescope. However,
concerns that their discovery might be pre-empted by others
prompted them to announce their discovery of 2003 UB313 (along with
another very large transneptunian object 2005 FY9) and
also their observations of another, 2003 EL61 in
late July 2005.
The image above shows the object in rather poor sky conditions
moving just 40" in a period of 3 days. The field of view is
approximately 1/7th the area of the full moon and shows just how
slow and distant the object is. For comparison the moon travels
the same apparent distance in about 75 seconds of time.
See more information here: