Light intensity is inversely proportional to the square of its distance. The light we receive from the Moon increases 50000× if we land there. But so does the Moon’s apparent size, spreading the increase in intensity over a larger area.
Flat-Earthers incorrectly claim the inverse square law means the Moon would be too bright if we land there, and they use the argument to “prove” it is impossible to go to the Moon. In reality, the inverse square law applies to a point source. For a large light source, its change in apparent size must also be considered.
Continue reading “Moonlight and Inverse Square Law”
Flat-Earthers often show us images of a lamp illuminating a dark wall to demonstrate —incorrectly— how night can happen on a flat Earth.
In the images, the areas farther from the lamp appear dark. Due to the inverse-square law, areas farther than the source of light receive less light. However, these areas still receive light nonetheless. From these dark areas, the lamp is still visible. This contrasts with what happens at night, that sunlight is nonexistent and the sun is not visible.
Continue reading “Lamp Illuminating a Dark Wall Demonstration”