Seeing Green: Color of the Cosmos. (Cosmology)
We live in a pale-green universe. That's the conclusion of researchers who analyzed the colors of some 200,000 galaxies as part of the largest galaxy survey completed to date.
The survey mapped the brightness and distances of galaxies in two giant swaths that together cover 5 percent of the sky. From those data, Karl Glazebrook and Ivan Baldry of Johns Hopkins University in Baltimore and an international group of colleagues constructed what they call the cosmic spectrum.
The result is a record of the intensity of radiation that the many galaxies in nearby regions of the cosmos emit at various visible-light wavelengths. The average color, which is what the human eye would see if an observer could view from afar all the light sources in the universe together, is a few percent greener than turquoise.
Glazebrook and Baldry note that although the universe doesn't have any green stars, the large number of old, red stars and young, blue stars combine to give the overall pale-green color.
The researchers assert that the survey, known as 2dF, or 2-degree field, is large enough to make it a representative sample of the local universe. …