Pluto is bigger than experts had thought as flyby looms

Associated Press

CAPE CANAVERAL, FLA.

Little Pluto is a little bigger than anyone imagined.

On the eve of NASA’s historic flyby of Pluto, scientists announced Monday the New Horizons spacecraft has nailed the size of the faraway icy world.

Measurements by the spacecraft set to sweep past Pluto today indicate the diameter of the dwarf planet is 1,473 miles, plus or minus 12 miles. That’s about 50 miles bigger than previous estimates in the low range.

Principal scientist Alan Stern said this means Pluto has a lower density than thought, which could mean an icier and less-rocky interior.

New Horizons’ 3 billion-mile, 91/2-year journey from Cape Canaveral, Fla., culminates Tuesday morning when the spacecraft zooms within 7,767 miles of Pluto at 31,000 mph.

Mission managers said there’s only one chance in 10,000 something could go wrong, such as a debilitating debris strike, this late in the game. But Stern cautioned: “We’re flying into the unknown. This is the risk we take with all kinds of exploration.”

“It sounds like science fiction, but it’s not,” Stern said as he opened a news conference at mission headquarters in Maryland. “Tomorrow morning, a United States spacecraft will fly by the Pluto system and make history.”

Discovered in 1930, Pluto is the last planet in our solar system to be explored. It was a full-fledged planet when New Horizons rocketed away in 2006, only to become demoted to dwarf status later that year.