I've been trying to find celestial phenomena that could act like nebula often do in Sci fi shows, i.e.,

  • A phenomena where a ship can hide from other ships
  • A phenomena which is difficult but possible to navigate and stay inside.

Nebula in reality are too diffuse to be able to do these roles, so I have found 3 celestial phenomena which might be able to do this.

  1. Stellar accretion disk. I'm not talking about protoplanetary disks.

https://www.nasa.gov/mission_pages/hubble/science/planet-eater.html The exoplanet WASP-12b is being devoured by its star and I'm curious if it could create a dense enough accretion disk of hot gas and charged particles to act as a smokescreen. Maybe if the distance of the planet to the star was smaller, like if the star was a white or red dwarf, the disk would be more dense.

  1. Mass Exchange between stars.

https://en.wikipedia.org/wiki/Roche_lobe Some binary stars systems exchange matter between themselves. This matter would be composed of gas and plasma. Could this matter be dense enough for hiding?

  1. Shedding supergiant.

The very outer layers of a supergiant might be cool and dense enough for a vessel to hide in.

I'm curious if any of my three candidates could fulfill the role of a nebula from scifi. And if they do, what could be the repercussions of hiding in one for the hider and seeker.

  • $\begingroup$ An accretion disk is way more dangerous than a nebula. Hiding inside plasma from stars doesn't sound much better. $\endgroup$ Jul 1, 2022 at 14:01
  • 2
    $\begingroup$ If it is dense enough to be capable of hiding a star ship, it is surely also dense enough to destroy any silly star ship which tries to go through at cosmic speeds. $\endgroup$
    – AlexP
    Jul 1, 2022 at 14:15

2 Answers 2


You are off by several orders of magnitude, I think. Clouds and nebulae-like object are opaque because they span for huge distance, so there is enough room for light crossing them to be noticeably attenuated.

Think of it like a fog bank: from afar it looks an opaque wall, while inside it you can see at some distance. At the distance where one would use a scanner, it would be like being close in the fog bank.

For your reference, the Sun's density is about 1.4 times that of water, that of Betelgeuse is way lower: the clouds from which they formed were therefore even less dense.

  • $\begingroup$ It doesn't help that Hollywood tends to use nebulae like fog banks (I'm lookin' at you, Star Trek: The Wrath of Khan!). $\endgroup$
    – JBH
    Jul 2, 2022 at 3:31

Dark Matter

What I love most about Dark Matter is that we've never found proof of its existence. Oh, we have some astronomical observations that are really hard to justify using our current mathematics without the existence of Dark Matter — but having never found a cup full to test, we don't actually know if it exists (or if it's just a mathematical band-aid because we haven't worked out better arithmetic yet).

And that's good for you, because that means we can (*ahem*) adjust the definition to suit our needs!

So, what's wrong with using Dark Matter as the very fog bank you need? Today we like to think that Dark Matter is something invisible. "Dark" in the sense that it's "unknown." But what if Dark Matter really was dark? What if there were stars aplenty that we know nothing about because we can't see them in any EM spectrum?

Yeah, baby! Modern science as technobabble! Your ship, nursing tragedy, flees to a Dark Matter nebula where it simply... vanishes.


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