Greetings from Pluto: Dwarf planet is bigger than scientists thought

On the eve of NASA’s historic flyby of Pluto, scientists announced Monday that the New Horizons spacecraft has nailed the size of the faraway icy world. New Horizons’ 3 billion-mile, 9½-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 1 chance in 10,000 that something could go wrong — like a debilitating debris strike — this late in the game.

We’re flying into the unknown. This is the risk we take with all kinds of exploration. … Tomorrow morning a United States spacecraft will fly by the Pluto system and make history.

Principal scientist Alan Stern

New Horizons has already beamed back the best-ever images of Pluto and big moon Charon on the far fringes of the solar system. Besides the revised size of Pluto — still a solar system runt, not even one-fifth the size of Earth — scientists have confirmed that Pluto’s north pole is indeed icy as had been suspected. It’s packed with methane and nitrogen ice. And traces of Pluto’s nitrogen-rich atmosphere have been found farther from the dwarf planet than anticipated. New Horizons detected lost nitrogen nearly a week ago.

Science Pluto