What you're looking at here is a blue thing that's actually directly behind the red thing. Due to gravity bending the light around it, it looks like that red dot is wearing the blue one like a bracelet. Astronomers are pretty excited about this effect, because it means that they can study things that are directly behind gravity sources, like large galaxies, without having to send a fleet of warships into space to destroy the obstruction, which is often cost prohibitive.
The trippy thing about this effect is that the gravitational lens can actually make multiple copies of objects in the sky, so you really have to know what you're looking for. In the next image, the objects marked "lensed galaxy" and "lensed quasar" are actually the same galaxy and the same quasar. They've just been cloned by gravity effects so that they look like they're ganging up on us.
The other cool thing is that by manipulating this effect, we can actually tell where invisible but terrifying objects like black holes are, which means it's our only chance against most of the later stuff on this list.