Our perception of blue as a colour is considered to have evolved only 20000 years ago. It is a shorter wavelength than reds. The red wavelengths are filtered out from our atmosphere which is the reason the sky appears blue except at dawn and dusk. Then water filters red again therefore blue light waves remain and therefore the water appears in the blue spectrum of colour.
Blue is one of the three primary colours which combined make white light. It has cultural, religious, military meaning. Natural sources of blue include lapis lazuli, azurite, sapphires, indigo plants and woad trees
Blue eyes do not have blue pigments in the iris but less melanin which means blue wavelengths of light are reflected back rather than absorbed as with darker eyes.
Google the colour of blue and see its history and meaning through out the ages as well as its science.
A piece below to blue .
A postcard to Mars
Caladin sat at the rim of Kina-36 -Zero - a blue star in the Tarantula galaxy.
“Ready the net.”
Poa sat at the aft of their teardrop ship. Finger poised to release the net for the explosion.
The luminous net comprised of alloys of tungsten and rhenium sprung out like a spider’s web. A childhood memory of frost on the webs covering a fence in a paddock, flicked before her. It was like lace had been draped all over the barbed wire. It had been this image which was the basis for her design of the lipton and photon collecting device – Nieth’s net she had called it after the Egyptian Goddess, weaver and creator of things in the universe.
Her heart raced thinking about how close she was to glory or annihilation each time she sat at the mouth of a black hole.
The penumbra of the blue star whirred. Her head could feel of the gravity spinning. Timing was everything when harvesting pure light before it collapsed on itself.
The boom rippled toward their ship. It was coming.
Moving closer Cala felt the herself stretch and then shrink as the speed of light stopped time around her.
A miniscule tug on the net meant the liptons had been released and their photons were already pulsing away from the dark matter. Suddenly she was whizzing back into space at lightning speed. The net held the mother lode of photon and first tier particles. The nebula was surrounded by a cloud of ice laden objects but that had now been obliterated leaving the largest expanse of dark matter between the Tarantula galaxy and the Milky Way.
With no gravitational resistance Cala pulled along by the net of photons travelled the ten parsecs toward the familiar system of the sun and earth.
“I hope you are watching back home folks. The starburst should reach you right about now.”
Suddenly Cala and Poa fell into the orbit of Mars. Cala took the chute of titanium and let the gravity of Mars catch her. The net expanded and shrunk suddenly as the photons from the lipton decay lit up. Cala pressed the jets in the small teardrop ship and using the weight of the tungsten net sling shot herself toward Earth.
“Almost there Cala!”
The familiar orb rose before them both. Cala had seen it many times. The earth turned before them changing from the familiar green blue to rose pink where the magnetic fields had failed and let the solar winds in. The ozone was weakened and no longer filtered the ultraviolet of the sun.
“Is this your last time Cala?”
Poa’s voice pierced Cala’s mind.
“Yes Poa. They said the next stem cell transplant won’t work. The mitochondria are too ionised.”
“What will be your legacy download Cala?”
Cala didn’t answer but watched diligently taking note of the coordinates of the red patches and blue patches as they waited for a full rotation of the earth to be completed.
“If this doesn’t work it won’t be long before there will be complete collapse of the ozone” warned Poa.
Cala felt the ship fire into its final journey back to earth. The net was heavy and ready to be spilled out over the dead areas of the electromagnetic fields. As Cala watched the tau and muons flare into their decay releasing electrons and photons she saw the electromagnetic field rebuilding. It was like she expected the flare of energy packets of photons forcing the electrons back into their orbits.
“You didn’t answer my question Cala.” urged Poa feeling relieved that their mission had succeeded so far.
“I’d like to learn to sail. Find out where the bluest ocean lies. Take a photo and send it to Mars. In case the colonists ever need to remember what blue looks like.”
Clare L Rolfe 2020