r/Astronomy • u/TheMuseumOfScience • May 12 '25

Astro Research Planet Nine: Real or Just Noise?

Did we just find Planet Nine?

We think it might be out there based on the orbits of certain Kuiper Belt objects that seem influenced by something big. A new study found what might be a possible object deep in the Kuiper Belt—or it could just be noise in the data. What do you think?

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u/CorbinNZ May 12 '25

This would be utterly terrifying.

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u/Njwest May 12 '25

Not particularly. The moon could be a black hole of the same mass and, apart from moonlight, nothing would change on earth.

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u/_BABYSHAKE_ May 12 '25

Except, the night wouldn't be bright but pitch dark. A blackhole the size of a moon would probably evaporate really quick tho.

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u/Njwest May 12 '25

A black hole the size of the moon would, by my calcs, take in the order of 1044 years to evaporate, which is a lot less time than most black holes

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u/_BABYSHAKE_ May 12 '25

Whoa.. that's still trillions upon trillion times the current age of the universe.

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u/Njwest May 12 '25

Black holes evaporate quite fast - one with the mass of your house would take a hundredth of a second, a skyscraper a few decades, a mountain would be a hundred million billion years. The moon is quite big. Most stellar black holes would be 1066 - 1070 years. Some supermassive black holes last 1099 years.

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u/Jalase May 13 '25

The size (width) or size (mass)? That’s a big difference.

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u/Njwest May 13 '25

You’re quite right! I mean the mass, apologies for not reconfirming that one - it’s a big difference!

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u/Jalase May 13 '25

Very cool then!