absorption spectrum
"An absorption spectrum is like a fingerprint; every element and compound will absorb one or more wavelengths of light. By determining *which* wavelengths are missing, the astronomer can deduce it's being absorbed by a specific element or molecule."
"In 1814 Joseph von Fraunhofer, a German optician, used a spectroscope to produce a spectrum of the Sun. He noticed that the spectrum contained a number of dark lines on a continuous spectrum. Fraunhofer had no explanation for these dark lines, but it was later discovered that they had resulted from sunlight passing through cooler gases in the Sun's atmosphere. A dark-line spectrum, called an absorption spectrum, is like a jigsaw puzzle with a few missing pieces. All stars show this type of spectrum. "
METAMIA is a free database of analogy and metaphor. Anyone can contribute or search. The subject matter can be anything. Science is popular, but poetry is encouraged. The goal is to integrate our fluid muses with the stark literalism of a relational database. Metamia is like a girdle for your muses, a cognitive girdle.