It has been known for some time that colors can be described by three numbers. If I show you light of a certain color and ask you to match it by combining lights of three other colors and varying their intensities, you'll typically be able to find a combination that looks indistinguishable. But the wavelengths you combine might be very different from the wavelengths I showed you. Light of the wavelength corresponding to yellow and light of the right combination of red and green wavelengths will look the same, even though they are physically quite different.
The Midnight Sun is a natural phenomenon that occurs in the summer months near the Arctic and Antarctic Circles, where the sun remains visible at the local midnight. This short, time lapse film was shot in June 2011 over 17 days and incorporates 38,000 images. The photographer/videographer traveled over 2,900 miles throughout Iceland. Midnight Sun(SL-vimeo, via)[more inside]
posted by zarq
on Oct 18, 2011 -
The average human eye has three types of cone cells, each of which is sensitive to a different wavelength range of visible light. The difference in the relative signal from the three cones allows us to distinguish colors. Unfortunately, since these sensitivity ranges overlap, there are some combinations of signals from the cones that can't be created by light emitted from a real object. These are the so-called "imaginary colors". However, by selectively overstimulating one or more types of cone, we can still perceive these colors; this is the principle behind the Eclipse of Titan, an optical illusion which produces both a green and a cyan that don't otherwise appear in nature. (Similar effects can be seen in the Eclipses of Mars, Neptune, and Triton.) [more inside]
posted by Upton O'Good
on May 10, 2010 -