What Color is the 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.

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.

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.