What Color is the Sun?

Ja11 Andy Warhol Sun

As much as I’d like to give you a straightforward answer to this question, I can’t. I can’t just say the Sun is yellow or white or purple. To really understand the color of the Sun, we need to talk about absorption and emission spectra.

Light from the Photosphere

Atoms absorb light. To be more accurate, different kinds of atoms absorb specific wavelengths of light, letting all the other wavelengths continue on their merry way. The result is what we call an absorption spectrum.

All the colors of the rainbow, except a few are missing.  This is an absorption spectrum.

All the colors of the rainbow, except a few are missing. This is an absorption spectrum.

The light we see coming from the Sun’s surface (a.k.a. the photosphere) has an absorption spectrum. The overall appearance is white or, according to some experts, a slightly greenish white.

But there’s more to the Sun’s color than just the photosphere.

Light from the Chromosphere

Sometimes, when an atom receives energy, it emits light. To be more accurate, different kinds of atoms emit light in specific wavelengths. We call this an emission spectrum.

No rainbow, just a few specific colors.  This is an emission spectrum.

No rainbow, just a few specific colors. This is an emission spectrum.

The glowing plasma that surrounds the Sun is called the chromosphere. The chromosphere appears to be a red or pink color, due mainly to light emitted by hydrogen atoms.

The light of the chromosphere is not nearly as intense as the light from the photosphere, but that doesn’t mean the chromosphere doesn’t contribute to the Sun’s overall color—whatever that color is.

There’s one more factor that influences the Sun’s color, at least as far as our Earthly perception is concerned.

Earth’s Atmosphere

Earth’s atmosphere tends to scatter blue light (which is why the sky is blue). So we see the Sun as a yellow-orange color because most of the blue light has scattered away, while reds, oranges, and yellows follow a more or less direct path straight from the Sun to your eye.

The Color of the Sun

So what color is the Sun? It’s every color, or rather it’s every color except a few that were absorbed in the photosphere, plus a touch of reddish pink from the chromosphere, minus a whole lot of blue if you’re observing the Sun from Earth.

Sources

Lecture 9: The Sun’s Photosphere and Chromosphere from Dmitri Pogosian at the University of Alberta.

Spectra and What Scientists Can Learn from Them from NASA’s “Imagine the Universe.”

Photosphere from Wikipedia

Chromosphere from Wikipedia

What Color is the Sun? from Fraser Cain, publisher of Universe Today (YouTube video).

What Color is the Sun? from the Stanford Solar Center.

4 Responses to What Color is the Sun?

  1. […] called absorption and emission spectrums. We touched on this in last week’s post entitled “What Color is the Sun?” Pictured below are rough approximations of the absorption and emission spectrums of hydrogen […]

    Like

  2. […] atoms and molecules absorb specific wavelengths of light, producing what’s called an absorption spectrum. Given the prevalence of sulfur compounds in Venus’s atmosphere, it seems like a safe bet that […]

    Like

  3. […] atoms and molecules absorb specific wavelengths of light, producing what’s called an absorption spectrum. Given the prevalence of sulfur compounds in Venus’s atmosphere, it seems like a safe bet that […]

    Like

  4. […] visible light to reflect off them. At one point, I wondered if I should color them based on their spectroscopic signatures, but that line of research got complicated really […]

    Like

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: