APOD: 2020 December 27 - Cosmic Latte: The Average Color of the Universe

Good afternoon, Rallypoint. Today's Astronomy Picture of the Day (APOD) is titled "Cosmic Latte: The Average Color of the Universe." Einstein began to derive his paper "On the Electrodynamics of Moving Bodies" with a simple thought experiment: what it would be like to run alongside a light beam. In that tradition, a group of scientists recently asked "What color is the universe?" To answer that question, they used the 2dF Galaxy Redshift Survey (released in 2003) that contains visible light data from over 200,000 observed galaxies. Smearing all those colors together (Red: 34.74%, Green: 33.79%, Blue: 31.47%) produces the color #fff8e7...dubbed cosmic latte. Sounds like a drink from an upscale coffee bar in Berkley. Based on observed redshift data, they suggest that blue (from younger, hotter stars) has been declining over the last 10 billion years or so.