Ghostly circles of radio emission, hanging out in space like cosmic smoke-rings, can’t be explained by current theories. And astronomers are excited to figure them out. 
Source: https://www.livescience.com/ghostly-circles-puzzle-astronomers.html
Only the Autodidact is Free
Ghostly circles of radio emission, hanging out in space like cosmic smoke-rings, can’t be explained by current theories. And astronomers are excited to figure them out.
Source: https://www.livescience.com/ghostly-circles-puzzle-astronomers.html