Ok there was some dispute here (see comments) about the factibility of a sun-weapon, the dispute is that if mirrors are too small (compared to target's distance), they are subject to the pin-hole camera effect regardless the fact that the mirrors are convex or not.
So is there really a limit for that? Is this answer right even in the case the mirrors can be crafted with unlimited precision and the right amount of curvature?
- We can have a curved mirror that focus sun-light into a specific spot
- We cannot do that if use billions curved mirrors that are placed far away?
To recap: is that really impossible to burn anything on Earth by placing a huge amount of mirrors on the moon?