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If a YouTube video I saw whether you can use moonlight to start a fire is to be believed, you cannot achieve higher temperature using lens than the source tempe
by dvh 4y ago
If a YouTube video I saw whether you can use moonlight to start a fire is to be believed, you cannot achieve higher temperature using lens than the source temperature, so your earth lens will achieve same temperature as 5cm lens from dollar store.
- hutzlibu 4y agoBut isn't the actual source the sun (6000K) and not the moon as it is acting only as a mirror? With a mirror you can also burn things if you focus sunlight, but the surface of the mirror stays cool.
- ben_w 4y agoAt a guess, the moon is a diffuse rather than a reflective surface, so it's going to be closer to a maximum of the lunar surface temperature than to solar surface temperature. An atmospheric lens, however, will reach a maximum of somewhat closer to solar surface temperature, though still lower because of scattering and absorption which definitely isn't trivial on this kind of scale.
- PaulHoule 4y agoThe moon is pretty dark, reflecting about 12% of the sunlight that falls on it https://www.universetoday.com/19981/moon-albedo/ https://www.universetoday.com/19981/moon-albedo/ If it had an albedo of 0% it would be a black body and be radiating only thermal radiation at its surface temperature; it's not too far away from that but it is reflecting some "black body" radiation from the sun representative of a higher temperature.
- bartislartfast 4y agoa 5cm lens from a dollar store can burn things in the focal point