Sun Dial

You find a box in the attic.

In this box, there is  a sun dial, like those found in gardens for timekeeping.  The flange that casts a shadow can be rotated.  Turning it  will adjust the energy output of the sun from zero (no energy output) to one hundred thousand suns (as much as a good-sized galaxy). Setting the sun dial back to its proper setting after modification may not be easy; being off by just a little bit may be disastrous for life on earth.