Astronomers have discovered an object in our solar system that is larger than Pluto. They are calling it the 10th planet, but already that claim is contested.

The new world’s size is not at issue. But the very definition of planethood is.

It is the first time an object so big has been found in our solar system since the discovery of Pluto 75 years ago.

The announcement, made today by Mike Brown of Caltech, came just hours after another newfound object, one slightly smaller than Pluto, was revealed in a very confusing day for astronomers and the media.

The new object, temporarily named 2003 UB313, is about three times as far from the Sun as is Pluto.

“It’s definitely bigger than Pluto,” said Brown, a professor of planetary astronomy. The object is round and could be up to twice as large as Pluto, Brown told reporters in a hastily called NASA-run teleconference Friday evening.

His best estimate is that it is 2,100 miles wide, about 1-1/2 times the diameter of Pluto.

Space.com article
Wikipedia page