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Interesting fact of the day: Not counting point sources of light, any source of light that doesnt appear as a single point will have the same brightness no matter what distance you happen to be from it.
In fact the opposite is true in a sense. Once you get close enough to an object that you can no longer see the whole object within your field of view, then it will get **less** bright as you get closer.
Amazingly this even applies to the sun. IF you were at the surface of the sun, just a few feet away (Such that 1 meter square of the surface of the sun was within your field of vision) it would only appear to be 93 lumens bright. That would be equivalent to only a 6 watt incandescent light bulb! Compare that to the brightness of the sun from earth which is a whopping 127,000 lumens.
@freemo Not entirely true. You are confusing (overall) brightness with surface brightness. Surface brightness, that is light power received per unit solid angle, does not decrease with distance, but since luminous area decreases with distance squared, so does overall brightness = solid angle * surface brightness. For this reason, photographing the Moon (same distance from Sun as Earth) requires the same exposure settings as a sunlit landscape, but Saturn (10x distance) 100x more (+6.6 EV)
@freemo Also, on the surface of the Sun, the area from with light reaches you, is 180ยฐx180ยฐ, way more than the 0.5x0.5ยฐ as seen from Earth. So you will be toast within a fraction of a second, although a 0.5x0.5ยฐ piece of the Sun would be the same brightness as seen from Earth.
Incorrect, but only because you seem to misunderstood what was asserted.
@freemo Well, you will certainly be toast very quickly, but you didn't define what "brightness" means, so the post was not unambiguous. To a layman, brightness usually means how bright something is lit by the light source (at a particular distance, that is). Surface brightness is a concept that needs to be introduced.
@AlphaCephei yes i should have been clear and said "perceived brightness of an object" to be more clear.
Little side note.. you are right of course you'd burn up, but that brings up an unrelated interesting fact:
The sun is very poor at generating heat. In fact the human body outputs significantly more energy per cubit meter than the sun does.
@freemo True, the heat production of a particular volume of the solar core has been likened to that of a dunghill of the same volume. The Sun is very ineffective at fusing hydrogen, that's why it last so long. But it is also a very big dunghill, so to say...๐
@AlphaCephei haha yup... big dung hill, minimized surface area (as a sphere), poor heat transfer at certain layers AND is sitting in a near-vacuum... so the heat builds up over time.
Another interesting fact, did you know the sun is not massive enough to cause fusion at all if it weren't for quantum tunneling? This effect causes just enough extra heat to allow the process to begin at all.
@AlphaCephei
Another little relevant point.. I did use lumens, and while you are correct my wording wasnt poor, lumens do not measure total irradiated energy (that is lux).. lumens is a particular measure of the amount of light falling on a surface. Which in this case, implied the eye.