Obvious theory - Mercury captured a primordial black hole in the recent past, and is slowly being devoured from the inside.
(Yes, the energy released by that process would quickly get very obvious. If you've got a passable hand-wave, audiences are very forgiving of plot holes in SciFi.)
Mirror without a paywall: https://archive.is/FInCm
Obvious theory - Mercury captured a primordial black hole in the recent past, and is slowly being devoured from the inside.
(Yes, the energy released by that process would quickly get very obvious. If you've got a passable hand-wave, audiences are very forgiving of plot holes in SciFi.)