Orbit Science / 40k - permanently hiding a constellation from the view of a planet?

[Feil]

In Warhammer 40000, humanity has colonized most of the galaxy, and there's a "warp rift" called the Eye of Terror, the size of a decent-sized dwarf galaxy, parked on one of the Milky Way's spiral arms. It glows, it's evil, and it's been there for about fifteen thousand years.

Suppose I'm the planetary governor of some place fifteen thousand and change light years away from said warp rift. Thanks to faster-than-light communications, I know what's coming a few years from now, and I've decided that the solution is to put a bunch of stuff between my planet and the Eye of Terror.

(Or, for a more real-life example, suppose I'm a terrestrial mad scientist who really, really hates Virgo.)

Can I orbit something up such that it would stay permanently between a planet and a given section of the firmament? How far, and how big, would it have to be, to make it work?

[bilateralrope]

For 40k, the easiest option would be to convert the planet to a Hive world. Most of the population won't get to see the sky and those that do will see a sky so polluted that none of the stars are visible. Though there is the worry that the AdMech were planning to use this opportunity to claim the planet for themselves and make it a Forge world when they told the governor about the Eye of Terror becoming visible to him.

But if you want an orbiting solution, that depends on where the constellation appears in the sky. Near the systems equator and you might be able to create a ring of debris around the star to block it that only requires orbital mechanics. The further it is from there, the more active you'll need to be keeping it in place. A massive engineering project either way.

[Cykeisme]

Feil, it has been some time since I have had the pleasure of saying hello (due in no small part to my own lack of presence I suppose).
"The Shadow War" is still one of my favorite pieces of 40k fiction, long form or short, official or otherwise.

Near the systems equator and you might be able to create a ring of debris around the star to block it that only requires orbital mechanics. The further it is from there, the more active you'll need to be keeping it in place.

Does the equator of a planet's rotation affect the orbit of a large amount of bodies into orbit (i.e. a ring)?

I am under the (possibly incorrect) assumption that the ring can be at any orientation relative to the planet's rotation, and that the axis/equator of the planet's rotation will not have significant effect on the ring's orbit.

Or are you referring to using the inertia of objects launched from the planet's rotation to reduce the amount of energy required to be imparted when launching all the orbital objects from the surface? If this is the case, then that answers my question, I suppose.
Although 40k is "soft" sci-fi in the sense that the various civilizations that appear in have spaceships that are capable of generating power and total energy far in excess of the amounts required for orbital mechanics around an Earth-like planet.

Edit: OH, I just realized that if the Eye of Terror was not directly above the equator of above the planet's pole, then a ring would not block view of the Eye for much of the year, as the planet orbits its sun...

[Eternal_Freedom]

It being over the equator is important if you want something to stay above the same point on the surface, this is what "geostationary orbit" means. Any other inclination and it will pass over the same spot every 24 hours, which isn't what we're looking for. For this to have any chance of working, you'd need some sort of powered orbit to blot out the Eye of Terror from the surface - or something large enough far enough away that it blocks out/eclipses the Eye from any point on your planets orbital path, but that would be...even more difficult I think.

[Cykeisme]

It being over the equator is important if you want something to stay above the same point on the surface, this is what "geostationary orbit" means. Any other inclination and it will pass over the same spot every 24 hours, which isn't what we're looking for.

Oh, d'doh.. I stupidly imagined the entire planet as a point, forgetting that the planet's size is significant in this scenario, and that different geographical locations on the rotating surface will not be affected equally. The only way we can treat the entire planet as a point, would be if the ring was as wide as the planet's entire diameter. My bad.

Suddenly, the idea of simply making everyone permanently stay indoors in a hive arcology (or in underground habitats) is starting to sound more workable :O

[bilateralrope]

I got my terminology wrong. A ring round the planet is only going to block the constellation from the surface directly under the ring. Maybe that's enough for some planetary governors because they don't care about people living outside it. But it's probably not.

For an unpowered orbit, you're going need the constellation to be aligned with the plane of the planets orbit. Then, if you can get enough stuff, you could build a ring of stuff outside the planets orbit that's constantly in the way. By enough stuff, we are probably talking dismantling the other planets in the system to turn them into the ring.

If the constellation isn't aligned with the plane of the planets orbit, you'll need a powered orbit.

Polluting the atmosphere so nobody can see the stars, then doing whatever you have to do to avoid angering the wider Imperium with a missed tithe is the easier option. Well, that or a strictly enforced curfew so that nobody goes outside at night. With servitors wandering the streets killing anyone who goes outside.

[Batman]

Why exactly is it 'important' people don't see this thing? Does it spread its evil influence via photons?

[bilateralrope]

Why exactly is it 'important' people don't see this thing? Does it spread its evil influence via photons?

Because somebody convinced the planetary governor that it would be bad to let people see it. Nobody is saying that they were right to do so.

[Batman]

So basically 'just because'. Fine by me, I was just wondering if maybe there was a somewhat rational reason behind it, not being very familiar with 40K.

[Eternal_Freedom]

Well the Eye of Terror is basically a star-cluster-sized gateway to Hell. So looking at it might be a legitimately bad idea. And trying to keep your population as ignorant of Chaos as possible seems to be a fairly standard MO for Imperial Governors.

Honestly though, the "keep everyone in the Hive City" idea seems the most workable.

[Lord Revan]

The thing to remember about the Eye of Terror is that it got that name because it was freaking the living daylights out of a Primarch (Logar IIRC) just by existing, so "can spread evil thru photons" doesn't really sound that odd. Especially when you consider that "Chaos" isn't exactly the same thing as "evil" so while a majority of the stuff chaos causes could be classified it's not so much "made of evil" as "made of discord and other destructively chaotic things"

[Feil]

I don't have any evidence that it's an effective action, but more because it might be insufficient than because it wouldn't be on the right track. 40k (when it's not too poorly written) is a place in which symbols and ideas have intelligence and agency, and will twist, unmake, and subsume human minds. I think it's plausible that blotting out the Eye of Terror would help, but it wouldn't be 40k if people weren't still drawn to stare at the partially blacked-out sky, 'transfixed with a dread not of this nor any world, but only of the mad spaces between the stars.'

[madd0ct0r]

How much of the night sky does the eye of terror take up?

You could block it out by launching big solar sail probes towards it. You only need enough to cover a stripe one planetary diameter 'tall' and one planet around sun orbit diameter wide. The sails don't need to move fast, just enough to keep splayed and out of planets orbit.
A dust could would have same effect but fall back in sooner.

[Feil]

Assuming maps are semi-accurate I'd ballpark it at 5000 LY plus or minus 3000 and roughly spherical. So at 15000LY distance, low end estimate Ω ≈ 0.06 st, high end estimate Ω ≈ 1 st.