this post was submitted on 15 Feb 2024
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The suns angular diameter is about 0.01 radian, so at a distance of 100km, the suns reflection will spread out to a disc about 1km across.
392MW over a disc that size is 500w/m2, which is weaker than direct sunlight.
They can aim each mirror individually though.
And each one makes a 1km2 spot.
It’s not the aiming, it’s that the sun is not a point source.
Yes; it is well known that if you look at yourself in a flat mirror, and then back up, your reflection will spread out bigger and bigger and get dimmer and dimmer, the further away you get.
Wait
“You” are the sun in this scenario.
As you back up, you fill a smaller and smaller fraction of the mirror. The reflection becomes less sun and more space.
I have a little reflective disc. I will bet you $100 that a reflection of a sunbeam off of it will be exactly the same size (i.e. the same intensity, since it's not getting any bigger) several meters away as it is a few inches away.
Try that in your backyard with a small mirror. You’ll find the sun’s reflection expands by about 1% of the distance.
Ooooh
Yes you're 100% right - it's not a point-source, so it will expand out slightly. I don't know the math well enough, but I believe if you if you say you do + it works out to about 1% of distance.