These are all the colors emitted by the Sun. Notice anything missing?

Illustration for article titled These are all the colors emitted by the Sun. Notice anything missing?

The Sun emits an impressive range of visible light. Some colors, however, are more strongly represented than others – while others are missing entirely.


The data depicted here was acquired by the Fourier Transform Spectrometer at the National Solar Observatory atop Kitt Peak, near Tucson, AZ. That data was originally translated into an awesomely named "Solar Flux Atlas" (described in a report by the same name), and identified solar wavelengths ranging from 296 to 1300 nanometers.

Granted, only a handful of those wavelengths are visible to the naked eye, which wavelenghts are depicted in the spectrum seen here [click here to see in very hi-res]. Each of the fifty rows covers sixty angstroms (i.e. 0.1 nanometers) of the visible spectrum (which itself spans roughly 4000–7000 angstroms, or 400–700 nanometers), increasing in wavelength from left-to-right, bottom-to-top. The result is a beautiful catalogue of the visible light emitted by our star – a catalogue that is, rather mysteriously, not entirely complete. Via NASA APOD:

It is still not known why the Sun’s light is missing some colors. Shown above are all the visible colors of the Sun, produced by passing the Sun’s light through a prism-like device. The above spectrum was created at the McMath-Pierce Solar Observatory and shows, first off, that although our white-appearing Sun emits light of nearly every color, it does indeed appear brightest in yellow-green light. The dark patches in the above spectrum arise from gas at or above the Sun’s surface absorbing sunlight emitted below. Since different types of gas absorb different colors of light, it is possible to determine what gasses compose the Sun. Helium, for example, was first discovered in 1870 on a solar spectrum and only later found here on Earth. Today, the majority of spectral absorption lines have been identified - but not all.

[NOAO and NASA APOD via The Science of Reality]


what's missing. purple?