The Carousel Lens is a unique magnifying portal into deep spacetime. A gravitational lens is a massive structure in space that bends light around it in such a way that more distant objects become more clearly visible to us. The Carousel Lens is a cluster of galaxies with seven other galaxies lined up behind it.
“Finding one such alignment is a needle in the haystack. Finding all of these is like eight needles precisely lined up inside that haystack.”
Through that lens is a line of sight taking us close to the edge of the observable universe. Both the skill and luck involved in finding an alignment of a stack of galaxies pointing to the edge of known space are staggering.
In the middle of that intergalactic telescope is an Einstein Cross. This is what one looks like:
An Einstein Cross is a gravitationally-lensed quasar, and apparently in this instance it becomes key for modelling the Carousel Lens. Looking at it, I like to think of it as a rangefinder halfway down the telescope, helping to target the Lens for the end of spacetime.