Surprise! Pluto is bigger than scientists thought

NASA's New Horizons settles the size debate. Pluto may be classified as a dwarf planet, but it's larger than many estimates.

Amanda Kooser
Freelance writer Amanda C. Kooser covers gadgets and tech news with a twist for CNET. When not wallowing in weird gear and iPad apps for cats, she can be found tinkering with her 1956 DeSoto.
Amanda Kooser

Charon and Pluto
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Charon and Pluto
New Horizons sees Pluto and its moon Charon. NASA/JHUAPL/SWRI

Pluto's ego took a major blow in 2006 when it was demoted from a full-on planet to a dwarf planet. It can take back some of that pride with the news that NASA's New Horizons mission has discovered it's a bigger space object than many scientists expected.

NASA announced Monday that Pluto is 1,473 miles in diameter, which the space agency says is "somewhat larger than many prior estimates." The determination was made using images collected by the probe's Long Range Reconnaissance Imager (LORRI).

"The size of Pluto has been debated since its discovery in 1930. We are excited to finally lay this question to rest," said mission scientist Bill McKinnon in a statement. NASA notes there has long been difficulty figuring out an accurate size for Pluto due to "complicating factors from its atmosphere."

New Horizons' journey to Pluto (pictures)

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New Horizons launched in 2006 on a multibillion-mile mission to study Pluto and its moons. It is scheduled for its closest flyby on Tuesday. NASA expects to learn much more about the dwarf planet and its petite satellites as the probe moves in for better images and a fresh round of data collection.

One estimate that New Horizons confirmed is the size of Pluto's largest moon, Charon. Charon clocks in at 751 miles across. Nix and Hydra, two much smaller moons, are around 20 miles and 30 miles across, respectively. We're still waiting to hear back on measurements of Kerberos and Styx, two even smaller moons known to orbit Pluto.