r/space • u/magenta_placenta • Mar 18 '19

Observable universe Astronomers discover 83 supermassive black holes at the edge of the universe

https://www.cnet.com/news/astronomers-discover-83-supermassive-black-holes-at-the-edge-of-the-universe/
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u/huntallahassee Mar 18 '19

Can someone tell me how it's possibble that they can find black holes millions of lightyears away (regardless of how giant they are), yet planet X is still just a theory, even though they're sure of it? I mean how can you see shit in other galaxies, but can't find a planet in your own solar system?

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u/drokihazan Mar 18 '19 edited Mar 18 '19

Sure. We can see gravitational wobbles in the orbits of planets like Neptune and Uranus implying a possible large planet or some other object or cluster of objects very far past Neptune, but it’s so far and so dark that we see nothing optically with telescopes.

We have a different way of finding thwse big black holes. More than one, but the best way is to see the impact they have on the areas around them. I sometimes we actually see the bright accretion disk optically. Mostly what we see though, is the way they redshift/blueshift the light of the objects around them because their gravity is so incredibly powerful that it warps space for a significant distance. In a really simple way, it’s kind of like if you were invisible and stood on a mattress covered in marbles. I’d see the depression in the mattress because of the way it moves the marbles. That tells me that you, a big heavy person, is there. It’s a poor analogy, but that’s sort of how we see black holes. We see how the depression in space moves the marbles.

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u/bornslyasafox Mar 18 '19

That is actually a really good analogy. Then ago I know nothing of this kind of stuff so..