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> The Moon's angular diameter is about 0.5 degrees. To match that angular diameter at 36,000 Km, we need a 5.4 Km wide object. The article doesn’t say it’s goi
by djrogers 8y ago
> The Moon's angular diameter is about 0.5 degrees. To match that angular diameter at 36,000 Km, we need a 5.4 Km wide object.
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.
- dsr_ 8y ago8x 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.