The Carina Nebula, The Hidden Universe

In 2001, some physicists put their heads together and asked: “What is the color of the Universe?”

By this they meant what color would an observer see, “if they had the Universe in a box, and could see all the light at once.”

“And,” they added, as if that question was too simple, “it wasn't moving.” They added this bit because, because of the Doppler effect, stars that are receding from Earth are redshifted – i.e. they appear redder than if they weren’t moving, relative to us.

Even though, as the New Scientist observed, the question might seem about as useful as “the ‘answer’ to life, the Universe and everything given in the Hitchhikers Guide to the Galaxy - 42,” the astronomers knew the spectral analysis would help them trace the history of star formation. So they forged ahead with the calculations and, in January 2002, captured the public’s attention when they announced their result.

Color initially heralded as the color of the universe.

“In space no one can hear you scream, which is probably a good thing,” the Guardian wrote in their coverage, “as scientists have discovered that the universe is a shade of turquoise.”

The Guardian’s reporter might have been glib, but many others embraced the color. The real problem was, the universe isn’t turquoise. The scientists had gotten it wrong.

A Several Billion Light Year Survey

The researchers had come up with their result with data from the 2dF Galaxy Redshift Survey: a spectroscopic survey of a “large volume of the Universe.” What does “large” mean? The survey area reached out several billion light years, and included more than 200,000 galaxies. It was the biggest survey ever done, and the first large enough to plausibly be “representative” of the universe.

The spectroscopic surveyors were measuring all the light energy in the universe, broken down into its component wavelengths – which correspond to different colors. White light is made up of a lot of different colors of light, which is why, if you shine a flashlight through a prism, you get a rainbow.

 And, if you shine all the light in the universe through a prism, you’ll see something like this:


The intensity of the cosmic spectrum at various wavelengths, and a representation of the colors they correspond to (though the range of light actually visible to the human eye ranges from about 4,000-7,000 angstroms).

The peaks and valleys on the line chart correspond to bright bands and dark bands on the spectrum, which indicate “the characteristic emission and absorption of different elements.” Older stars emit and absorb different elements than younger stars, which results in different colors with different spectra. The younger the star, the bluer it is. The older the star, the redder it is. As time goes by and stars age, the cosmic spectrum changes too.

Starting with this spectroscopic information, the researchers were able to determine that most of the stars in the universe are more than 5 billion years old. According to them, “due to the decline in reserves of interstellar gas for forming new stars,” they just don’t make them like they used to. 

A Whiter Shade of Pale

So far so good -- all of this research seems to be right. The real mistake happened when the scientists used software they found online to simulate mixing that spectrum together into one color of light. When they did it, they didn’t pay enough attention to the software’s white balance.

Because of the way different shades of light interact, “the color of the Universe” will look different depending on where you are. In broad daylight, it’s redder. Under indoor lighting (which is much yellower than daylight) it’s blue. Color engineers, who had seen the physicists’ publication and double-checked their data, discovered that the software the researchers had used was calibrated to a slightly redder, warmer light than typical, resulting in green.

The same photo processed with the white ceramic as “white” on the left, and the red ceramic as “white” on the right

"It is embarrassing," researcher Karl Glazebrook said, when announcing the correction two months later. "But this is science. We're not like politicians. If we make mistakes, we admit them. That's how science works."

If you’re viewing all the light in the universe at once, you’re probably not viewing it under any light at all. The light conditions the physicists ultimately settled on, when correcting their error are, “for looking at the Universe from afar in dark conditions.” And under those conditions, the universe is probably the following, very pale shade of beige.

Glazebrook seemed chagrined to have to issue a media correction to a footnote that was ultimately inconsequential to the study’s central findings about the history of the cosmos, and was disappointed that the true color was so boring. “It looks like beige," he said. "I don't know what else to call it. I would welcome suggestions."

The astronomers eventually settled on “Cosmic Latte,” selecting it from a top ten list that included such tough contenders as “Primordial Clam Chowder”, “Univeige”, and -- presumably in reference to the white balance snafu -- “Astronomer Green.”

To their credit, these would all look great on a crayon. But, call it what you want, beige is still beige. It turns out that if all the stars and all the planets in all the galaxies were before you in a terrifying, brilliant, impossible box, the color would you see (while no doubt experiencing a transcendent feeling of oneness) is the most boring color in the world.

This post was written by Rosie Cima; you can follow her on Twitter here. To get occasional notifications when we write blog posts, please sign up for our email list

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