Blue is my favorite color...

But which blue is the sky?

Did my photo even capture the right color?

...so when I heard that Alexander von Humboldt had a cyanometer to measure the blueness of the sky, I decided that I need one, too.

What is "sky blue"? I've taken painting classes and am not sure I've ever achieved sky blue. I remember that Dr. Raabe was looking for a sky-blue flower. I wonder if he ever found it. And measuring its wavelength seems like cheating.

References

• Why the Sky is Blue: Discovering the Color of Life
• Horace Bénédict do Saussure's cyanometer.
• Prussian blue, the first modern synthetic pigment is what Humboldt used.
• Cyan (too green), was originally the cornflower
• Cornflower blue has little green
• Sky blue
• Some nice blue flowers: tweedia
• True blue flowers

From Royal Society of Chemistry