New Horizons Reveals the True Size of Pluto and Charon During Historic Flyby

NASA's New Horizons spacecraft has finally made its closest approach to the tiny dwarf planet. Now, scientists have announced that it's settled a debate that's circulated among researchers for years: the size of Pluto.

"The size of Pluto has been debated since its discovery in 1930," said Bill McKinnon, one of the mission scientists, in a news release. "We are excited to finally lay this question to rest."

Pluto's newly estimated size actually means that its density is slightly lower than previously thought. In addition, the fraction of ice in its interior is slightly higher, and the lowest layer of Pluto's atmosphere, the troposphere, is shallower than previously estimated.

It isn't only Pluto that's been measured, though. Scientists have also used observations of Charon to reveal that the moon is 751 miles across.

"We knew from the time we designed our flyby that we would only be able to study the small moons in detail for just a few days before closest approach," said Alan Stern, New Horizons principal investigator, in a news release. "Now, deep inside Pluto's sphere of influence, that time has come."

The new details tell the researchers a bit more about the Pluto system. With that said, researchers are still unsure about the other moons-for now. Data sent back from New Horizons will hopefully shed more light on the distant system.

Currently, New Horizons is speeding away from the system and toward the Kuiper belt to make even more discoveries.

Want to learn more about the New Horizons mission? Check out NASA's website.

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