Yeah, I remember seeing that thread about 8-10 mos. ago, but didn't follow up on it for some reason. Is that where that 250 octillion lm. figure came from? There are all kinds of resources around, probably many here on CPF, to calculate various things about light sources, but my brain is way too fried at the moment to attempt any of them!
The sun ain't really all that yellow at noon. CCT ~ 5600K in summer near the equator. It just looks yellow by comparison to the sky. If you take a 5600K LED neutral-white (on the Planckian Locus) torch which can easily match the sun in lux at very short distances (
), it actually looks only very slightly different from the sun at noon (relatively clear, unpolluted sky) on a white surface. Near sunrise or sunset, all bets are off. Sunlight becomes very yellowish at these times- a torch or CFL at 4100K CCT, on the Planckian, will look positively pinkish by comparison!
About blowing up planets with a "SunnyBeam" (Disclaimers: I just came up with this name; did a search of CPF- no hits; I'm not trying to step on anyone's toes if this name is already used! In the "explosion" section of this post, I am in no way trying to threaten, harass, impugn, belittle, or disrespect anyone living on planets, or sufficiently close to planets, which could conceivably be so affected, however close this may be. The writer of this post is, in fact, such a person. This post is intended to be a very bizarre continuation of the humor already beginning to be hinted at by other posters.):
If our Sun were directed at a rocky planet, the planet would probably vaporize, starting with the exposed side, in rather short order.
The gravity of the instantaneously remaining planet at each instant would try to reform the remaining planet material back into a sphere, since gravity overwhelms material strength at this scale, but the explosive forces and inertia would make this far too slow and weak for it to noticeably happen before the entire planet was vaporized/exploded, methinks. It would probably be similar to our nation's Capitol buildings in
Independence Day.
The vaporized side of the planet would expand with explosive force, blowing the remaining piece of the planet apart.
If the beam were left "on" long enough, much of the gas and debris would be expelled so far away that they would have no chance of gravity reforming them back into a planet, methinks.
If directed at a gaseous planet, it would probably just blow the gas all over the place.
In either case, the intense force of collecting the solar wind would have to be balanced somehow by the reflector or by innumerable immense rockets on the other side of it, or focus would become impaired after some amount of time. I have no idea if gravity of the sun would be strong enough to resolve this force or not. Probably not, for a thin reflector.
Since gravity and radiation both basically seem to follow the inverse square law AFAIK, the forces should be reasonably balanced across the reflector, at least if the reflector is many times farther from the sun than the sun's diameter, which it would have to be for optimal focus anyway, and to keep it from vaporizing.
Quote:
Originally Posted by Nitro
Interesting idea. It just may work. I'm game! 
Although, if it were aimed at a planet, I think "set on fire" would be an understatement. With that much energy I think it would instantly disintegrate it.
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How Many Lumens Does Our Sun Produce?
Re: How Many Lumens Does Our Sun Produce?
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