The Eleventh Planet

Astronomers have found another planet-sized object in the outer solar system:

It is one of the largest objects ever found in the outer Solar System and is almost certainly made of ice and rock.

It is at least 1,500km (930 miles) across and may be larger than Pluto, which is 2,274km (1,400 miles) across.

The uncertainty in estimates of its size is due to errors in its reflectivity.

A similar-sized body named Sedna was discovered last year, so this is the eleventh planet (for a generous definition of "planet - however, applying that term to Pluto is probably being generous...)