The moon may become a planet

London, Feb 20: The Earth’s moon could be among more than 100 planets added to the solar system, according to leading scientists at Nasa, reports the Independent. Along with Titan and Enceladus, which orbit Saturn and Europa, and Ganymede, which orbits Jupiter, the moon has all the features of a planet.Alan Stern, principle investigator of Nasa’s New Horizons mission to Pluto, along with five colleagues, has written a manifesto rewriting the definition of what constitutes being a planet.

The new definition, proposed last week by the International Astronomical Union (IAU), basically says every round object orbiting the Sun is a planet, unless it orbits another planet. But there is a big caveat: If the center of gravity, called the barycenter, is outside the larger object, then the smaller object is a planet. That wording elevates Pluto’s moon Charon to planethood, an idea some astronomers have criticized.

But here’s the thing. Earth’s Moon was born in a catastrophic collision more than 4 billion years ago. It started out very close to the planet but has been moving away ever since. It’s currently drifting away about 1.5 inches (3.74 centimeters) every year.

For now, the system’s barycenter is inside Earth. But that will change.

“If the Earth and Moon do survive, then the barycenter will eventually move outside the Earth as the Moon recedes,” Laughlin told SPACE.com. “At that point the Moon would be promoted to planetary status.” [What would we call it?]

None of this would occur for a few billion years. And Earth and the Moon would have to survive a host of remote catastrophe scenarios along with the predicted swelling of the Sun into a red giant, which Laughlin and others have previously said might engulf and vaporize our planet (unless we can figure out a way to move it).

Other astronomers have noted that it is possible there are three-object systems yet to be found in the outer solar system. If they are all round and have that certain barycenter thing happening, then they’d be called triple planets under the new definition.

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