Originally published at: https://boingboing.net/2020/04/29/little-black-hole-orbits-large.html
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Little black hole… oh yes tiny! Just 150 MILLION times the size of the sun. Still very interesting, thanks!
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Well, looks like wikipedia is now going to eat up what should have been another productive coding morning. Thanks a bunch.
Seriously though, thanks. I love this stuff and educational for the kiddos.
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Hmm…I’m beginning to suspect that “modeled the timing” is science-code for “played with a spirograph”
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Predicted to within four hours? Still more accurate than predicting when the comcast repair guy will arrive.
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How bright would it be for a planet orbiting a star in that galaxy? Would it be this tremendous flash? For a civilization in that galaxy, think about what it would do to their religion: god turning on the light every few years-- at some fairly random rate but always from the same point in the sky.
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18,000,000,000 time the size of “our” sun…
25,068,600,000,000,000,000 meters in diameter
78,755,329,595,781,100,000 meters Circumference
8,324.44 light years to travel around the circumference
This is my megalophobia
Even if my calculations are wrong by 99%, that’s still 83 years or, a lifetime travelling at the speed of light. 
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18 billion refers to the mass of the black hole, not its size. The size would be its schwarzschild radius.
= 53,172,525,247 km according to an online calculator, or 355 AU. Which is still pretty huge.
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Should be interpreted as the MASS of our sun. In a black hole the mass of our sun would be crushed down to an area maybe a mile across.
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Phew… I was panicking myself over the the fact this was huge, turns out it was only big.
Thanks for the correction.
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Yes I’ll put my hands up to my mistakes, just ask my kids. 
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I expect these black holes will merge eventually. I remember reading Stephen Hawking’s recollection of how he calculated what would happen during a merger. He mentioned that he solved it while he was getting into bed.
At the time I was thinking “well how hard could it have been if he solved it getting into bed”. The rub of course is that his disability made the process of getting into bed quite long indeed.
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But isn’t the radius actually infinite due to the curvature of space? 355 AU is just the circumference divided by 2π?
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I think that’s correct. Technically it’s not the radius of the black hole itself, but rather that of the imaginary sphere within which a given mass will become a black hole. But I’m no astrophysicist.
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That light is hard ionizing radiation, mostly gamma rays and x-rays. If it’s lighting up your sky, I don’t think you’ll last long enough to enjoy the view.
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A delightful description!
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To sort of wrap your head around at how compact black holes are, if the Earth were a black hole, it would be the size of a marble.
It is unfathomably dense.
A super massive black hole is still huge, though. Thanks to Mr. Shiv for the calculation.
So my question is - won’t this eventually get swallowed? Is that orbit stable? What sort of energy release are we looking at when they collided?
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Show the vid to the repair guy next time he shows up. “See? That little black hole is better than you!”
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The awesome people of JPL and Caltech ran the Spitzer program for NASA. Spitzer was technically retired in January 2020 so this was one of its final discoveries. It ran out of coolant in 2009 and they got another ten years worth of “warm mission” out of it. The story of how they caught this is pretty pretty neat. The telescope was 158 million miles from earth when it made these observations and they just lucked out that OJ 287 was within the sites. We would have missed it from over here.
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Yes I think you can only talk about the circumference of an event horizon.
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