Pluto is larger than thought, has an ice cap, NASA probe reveals

“Pluto is not disappointing,” said principal investigator Alan Stern, of the Southwest Research Institute in Boulder, Colorado, during a NASA briefing here today (July 13). [See a video of Alan Stern discussing Pluto’s size]

As New Horizons closes in, the spacecraft made the most precise measurements to date of Pluto’s size using methods similar to those employed by NASA’s Voyager spacecraft. The new diameter of the dwarf planet makes it larger than fellow Kuiper Belt denizen Eris, which is 1,445 miles (2,326 km) in diameter.

Previous estimates for the size of Pluto had put its radius at 1,430 miles (2,301 km). But Pluto now stands as the undisputed king of the Kuiper Belt.

“This settles the debate about the largest object in the Kuiper Belt,” Stern said.