# Is there a dominant colour in our universe?

Gold Member
It may be a strange question, Is there a dominant colour in our universe?
ignoring black and white. I have looked but can not find any thing.

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mezarashi
Homework Helper
Color? The concept of color comes from the way our eyes work. Since we can view a range of electromagnetic radiation known as the 'visible spectrum', we've assigned names to different frequencies. So are you suggesting that a certain frequency within this very limited visible range is more commonly emitted?

Gold Member
Yes, as a guess i would say blue then red, after searching through random pictures.

mezarashi
Homework Helper
That just doesn't sound very justified... or scientific atleast, considering you were using the "universe" as your domain, random pictures on google are just things relatively earthly.

honestrosewater
Gold Member
Would it be reasonable to look to the colors emitted by stars?

SpaceTiger
Staff Emeritus
Gold Member
Is there a dominant colour in our universe?

http://www.pha.jhu.edu/~kgb/cosspec/ [Broken]

As was already said, color is to some extent a result of how the human eye works, particularly the colors you listed (black and white). There are some colors, however, that can be roughly matched up with a particular wavelength of light. Red and blue, for example, correspond roughly to 800 and 400 nm, respectively. The color derived above is just sort of an average that we would see if we were to view all of the light of the universe at once. It's not a constant because the universe is evolving with time (it mostly gets more red), but it won't have changed much in the past billion years.

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Gold Member
Exactly thanks Space Tiger.

Gold Member
mezarashi said:
That just doesn't sound very justified... or scientific atleast, considering you were using the "universe" as your domain, random pictures on google are just things relatively earthly.
Sorry i meant random pictures of stars.

Mk
What range of

A) electromagnetic frequencies
and/or
B) electromagnetic frequencies we can see

are MOST commonly found in the universe?

How's that?

SpaceTiger
Staff Emeritus
Gold Member
Mk said:
What range of

A) electromagnetic frequencies
and/or
B) electromagnetic frequencies we can see

are MOST commonly found in the universe?

How's that?
The CMB is the dominant form (by energy density) of radiation in the universe. It's at millimeter wavelengths. The dominant form of optical light, as can be seen in the link I gave, is in an emission line at around 650 nm, which is red light. This is the Balmer alpha line of hydrogen, commonly seen in regions with heavy star formation activity.