Right, ‘rogue planets’ are accepted science I think.
But distant ones would be very hard to detect?
As for motions cancelling out… that could happen now and then, of course.
But it would be a temporary condition. I was wondering about a more stable situation, hence the thought of an object in a Great Void…
All a rather abstract thought experiment, really…
I would think that most rogue planets would generally have a pretty high velocity relative to their original star systems, assuming they were formed in star systems. After all, they got flung out of the system, which takes a pretty good velocity.
There are probably rogue planets that formed out of small gas clouds that weren’t large enough to create a star, though.
I assume when they said “great void” earlier in the thread they mean the space between galaxies. I am not sure what the escape velocity is to get out of the galaxy but I suspect it is more than getting out of a solar system.
It’s a big universe so I would expect some planets have been flung into the “great void” but I’d think most stay in the galaxy they started in. WAG on my part though.
The great void is a particular location in space, also known as the Boötes void.
I don’t think it’s anything special - just a place where there are few galaxies through randomness and the filamental structure of the universe.
There are a LOT of rogue planets out there. Probably far more of them than stars. Estimates are as high as 4-100 rogue planets for every star in our galaxy.
We find them through two major techniques: microlensing and direct imagery. The furthest rogue planet we have directly imaged is about 1300 LY away, pretty much in our backyard. The technique has definite distance limits.
Microlensing occurs when a star passes in front of a distant rogue planet, its gravity forming a lens and temporarily magnifying the planet enough to see. This is an extremely rare event, but rogue planets are so numerous that we’ve found close to 100 this way. We can see them across the galaxy with this method.
Some rogue planets move extremely fast. A planet that passes close to the supermassive black hole at the center of the galaxy could be accelerated up to 5% the speed of light. Most of those would probaly be found in intergalactic space, since they travel faster than escapevelocity for a galaxy, and the space between galaxies is massive compared to the space galaxies themselves take up.
We have measured similarly ejected stars’ speeds, and the fastest one we found was going 1.5 million mph relative to the average stars near it… But planets around stars that interact with black holes can accelerate even faster due to interactions between all three bodies.
Looking for rogue planets is one of the goals of the upcoming Nancy Roman Grace telescope, and it is expected to find many hundreds of them.
Other way around. The planet passes in front of the star, which (when you’re far enough away) momentarily focuses the light of the star, making it briefly brighten in a distinctive way.
And there probably are a decent number of rogue planets in the intergalactic voids (not a high density of them, but then, the voids are very large), but there’d be no hope at all of detecting them, by any means.
We’ll just have to fly there in the Skylark of Space. Go out and have a look?
Come up, Dick Seaton, get it built!
Yeah, I got that backwrds. I should have remembered the star brightening. I was probably thinking about the technique of using the sun as a lens to observe exoplanets. But yeah, in this case the planet moves in front of the star, temporarily brightening it.
I want one!