Will Pluto regain its planetary swagger? Scientists are pushing for it


Will Pluto regain its planetary swagger? Scientists are pushing for it

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This high-resolution image captured by NASA's New Horizons spacecraft shows the bright expanse of the western lobe of Pluto’s "heart," or Sputnik Planitia, which is rich in nitrogen, carbon monoxide and methane ices. (NASA/JHUAPL/SwRI)

A decade ago, poor Pluto got some unsettling news.

It wasn't really a true planet, the International Astronomical Union said. Pluto was demoted to a more minor player in the solar system, a dwarf planet at best.

But a handful of NASA scientists are leading a charge to redefine the word planet in a bid that could give Pluto back its planetary swagger.

Because, really, being a planet is better, they said.

"In the mind of the public, the word 'planet' carries a significance lacking in other words used to describe planetary bodies," the group wrote in a proposal to IAU. "In the decade following the supposed 'demotion' of Pluto by the IAU, many members of the public, in our experience, assume that alleged 'non-planets' cease to be interesting enough to warrant scientific exploration."

The group, which includes Sol Alan Stern, the principal investigator of the New Horizons mission to Pluto, notes that the shaming of Pluto was not the intent of the IAU.

IAU's definition of planet in 2006 changed to an object that must circle the sun without being some other object's satellite and be large enough to be rounded by its own gravity, but not so big that it begins to undergo nuclear fusion like a star."

Pluto didn't cut the mustard following the discovery of other large objects in the Kuiper Belt.

Now, the scientists on Pluto's planetary team claim a common question they hear is: "Why did you send New Horizons to Pluto if it's not a planet anymore."

The proposed new definition is a bit of a mouthful:

"A planet is a sub-stellar mass body that has never undergone nuclear fusion and that has sufficient self-gravitation to assume a spheroidal shape adequately described by a triaxial ellipsoid regardless of its orbital parameters."

But can be summed up with "round objects in space that are smaller than stars." (This is the elementary school definition, the scientists note).

It's in the hands of the IAU to rule on the plan. If it's approved, Pluto may indeed regain its planetary prowess.

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