The debate over Pluto’s planetary status has been ongoing since its reclassification as a “dwarf planet” in 2006 by the ...

If confirmed, that size would make it the second largest known TNO. As a comparison, Pluto’s diameter is 1,477 miles (2,377 km). Bad news for Planet Nine?

Giant, ridge-like structures of methane ice, known as "bladed terrain," may be much more abundant along Pluto's equator than previously realized, a new study suggests.

Pluto has just been found to be ever so slightly bigger than we thought, having a diameter of 2,370km. The measurement was made by the New Horizons probe which is just about to flyby the dwarf world.

Pluto "once had an internal ocean that was global in scale," explained Cruikshank, harkening back to a distant time when Pluto was still warm from the collisions that led to its birth.

Brown previously reported that UB313 was thought to be larger than Pluto and estimated that it was most likely between 1,398 miles and 2,175 miles in diameter.

The Hubble Space Telescope may be getting old, but it still has excellent spotting power — witness its discovery of a fourth moon of Pluto, which is between 8 miles and 21 miles in diameter.