Well, at the surface, when the rays are hitting perpendicular to the planet, it's 1000 W/m^2 (approx). Of course the real problem is they are measuring the lig

Well, at the surface, when the rays are hitting perpendicular to the planet, it's 1000 W/m^2 (approx). Of course the real problem is they are measuring the light in terms of incandescent bulb power draw, rather than something useful like lumens or candela, but due to a century of ubiquitous light bulbs, we've been rating light in the wrong units.