<p>If planet 9 is not a planet but a black hole how can we find it? Can we see gravitational lense or infrared/gamma light?</p>

CC BY-SA 4.0
2022-01-13T14:52:36.937Z
I'd presume that microlensing events, if you looked in the right place at the right time, would be possible.
WarpPrime
CC BY-SA 4.0
2022-01-13T15:02:00.107Z
And for a sense of scale, we'd be talking about a BH roughly the size of a softball or large orange.
eps
CC BY-SA 4.0
2022-01-13T15:04:42.540Z
Its impossible to any blackhole if it is "silent". Although its still a tough job to detect supermassive blackholes, In your case difficulty of detecting a black hole of radius just 4.4 cm with an optical ground telescope depends on how far it is away from the sun. Gravitational lensing will help
Kavin Ishwaran
CC BY-SA 4.0
2022-01-13T15:25:59.753Z
Does this answer your question? [How would a small nearby black hole be detected and confirmed as such?](https://astronomy.stackexchange.com/questions/33535/how-would-a-small-nearby-black-hole-be-detected-and-confirmed-as-such)  See also: https://astronomy.stackexchange.com/questions/27983/could-planet-nine-be-a-tiny-black-hole-or-an-exotic-compact-object-such-that-it and https://astronomy.stackexchange.com/a/36882/2531
ProfRob
<black-hole><planet><solar-system>
If Planet 9 is a primordial black hole with a mass of 5 Earth, is it possible to detect it in a ground telescope? What should we seek in this case?
Robotex
# If Planet 9 is a primordial black hole with a mass of 5 Earth, is it possible to detect it in a ground telescope? What should we seek in this case?

(Asked by: username_0 on 2022-01-13)

If planet 9 is not a planet but a black hole how can we find it? Can we see gravitational lense or infrared/gamma light?

**Tags:** black-hole, planet, solar-system
> **Comments:**
> **username_1**: I'd presume that microlensing events, if you looked in the right place at the right time, would be possible.  
> **username_2**: And for a sense of scale, we'd be talking about a BH roughly the size of a softball or large orange.  
> **username_3**: Its impossible to any blackhole if it is "silent". Although its still a tough job to detect supermassive blackholes, In your case difficulty of detecting a black hole of radius just 4.4 cm with an optical ground telescope depends on how far it is away from the sun. Gravitational lensing will help  
> **username_4**: Does this answer your question? [How would a small nearby black hole be detected and confirmed as such?](https://astronomy.stackexchange.com/questions/33535/how-would-a-small-nearby-black-hole-be-detected-and-confirmed-as-such)  See also: https://astronomy.stackexchange.com/questions/27983/could-planet-nine-be-a-tiny-black-hole-or-an-exotic-compact-object-such-that-it and https://astronomy.stackexchange.com/a/36882/2531  

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## 0 answers

