Reply to post: Re: Okay, planets. Why not ?

Planets may lurk in harshest environments. Not that Novell NetWare server you can't unplug – black holes

Rich 11 Silver badge

Re: Okay, planets. Why not ?

Black holes suck in everything, including any energy that might be around.

But only at the event horizon. Imagine a photon generated at a point somewhere in the accretion disk. If it happens to be emitted directly towards the black hole it will end up being sucked in (assuming it doesn't strike anything else first). If it is emitted in a direction that will just miss the event horizon it will swing around the black hole and maybe even head back almost towards the point where it was generated. If it is emitted off to one side it could pass round the black hole and head out into space, possibly even appearing to a distant observer as if it had passed through the black hole. But if it is emitted directly away from the black hole then it will escape quite comfortably, even though to an observer higher up the gravity well it will appear to take longer than a simple distance-over-velocity calculation would suggest. So a gamma ray emitted from the accretion disc could end up striking a planet in the outer disc, generating a particle shower and ultimately heat.

(All of the above is a simplistic treatment; the photon's path would also be affected by the frame-dragging effect caused by a spinning black hole.)

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