As it explains, the mysterious 'radio circles' detected in outer space have no known cause. Most distant object in outer space that emit radio waves also emit other types of radiation of other wavelengths but not these objects which is part of why they are so strange. One of the problems in theorizing a possible cause is that we still not sure roughly about how far they are away they are as their approximate distance away is currently very hard to determine.
There is a pretty wild theory mentioned in this video that they are the sign of the entry-exit points to huge space worm holes! I would find it nice if that theory proves correct but somehow I think its unlikely but, who knows!

YouTube&t=609s

@humy
"... I think its unlikely but, who knows! "

I agree. Dr. Who is probably the only one that knows.

here is a video about a proposal theory that some ring galaxies are actually wormholes and also explains these 'radio circles';

YouTube

As this video explains, even if these proposed worm holes exist, we probably still wouldn't be able to use them for space travel. Pity.

@humy
Well even if we COULD use it for space travel there is that pesky part where the dam things are a few thousand light years away at best.