Re:Chinese city to launch man-made moon to light up skies
by dsr_ on Thursday October 18, 2018 @11:28AM
(#18249106)
8x as much light as the moon is the same angular diameter and 8x more reflectance, or the same reflectance and 8x as much angular diameter. I suppose they could mean "8x as much reflectance but an unknown smaller insolation equivalent", but then they might as well say "we're putting a big spot light on a high-altitude balloon".
The relative sphericity of the moon is nearly immaterial here: when the moon is in full phase, do you see notable dimness around the edges where less sunlight is reflected away from you? Increasing the albedo to a near-perfect mirror cancels it all out.
The article doesn’t say it’s going to be as big as the moon - it only says it’ll be 8x brighter. You’re also forgetting about the relative shapes of the objects: the moon, being round, reflects what light it does in all directions, while a designed mirror can be made to reflect it all in one specific direction.
All that said, I don’t think this will work, but not be of your math.