The other colours pass through the Earth's atmosphere to reach us, but because of the great abundance of blue light wavelengths, our eyes see the sky as blue. Technically, the short wavelengths that scatter across the sky correspond to the colours blue and violet, making the real colour of the sky a bluish purple.
At noon, when the Sun is overhead it appears white. This is because the light travels a shorter distance through the atmosphere to get to us; it's scattered very little, even the blue light. During the day the sky looks blue because it's the blue light that gets scattered the most.
Actually, the sky was orange until about 2.5 billion years ago, but if you jumped back in time to see it, you'd double over in a coughing fit. Way back then, the air was a toxic fog of vicious vapors: carbon monoxide, carbon dioxide, nitrogen, cyanide, and methane.
This is because the sun emits a higher concentration of blue light waves in comparison violet. Furthermore, as our eyes are more sensitive to blue rather than violet this means to us the sky appears blue.
There you have it - the sky is blue is because of Rayleigh Scattering by the nitrogen and oxygen molecules in the atmosphere. And the ocean is blue because of Rayleigh Scattering by the water molecules that make up the water, as well as reflecting the sky.
Today we are celebrating the birth of one of the most important scientists and educators of the 19th century, John Tyndall. The Irish physicist was born on this day in 1820 and is remembered by many as the man who first explained why the sky is blue.
Scientifically, purple is not a color because there is no beam of pure light that looks purple. There is no light wavelength that corresponds to purple. We see purple because the human eye can't tell what's really going on.
Space is 'beige'
The researchers used a colour-matching computer programme to convert the cosmic spectrum into a single colour visible to humans. They concluded that the average colour of the universe is beige, not too far off from white.
If we judge by the most prominent color, the sky is violet. But the sky appears blue due to the limitations of our eyes. Our sensitivity to light decreases as we reach the shortest wavelengths of the visible spectrum. The violet is there, but our eyes detect it only weakly.
The atmospheres of the two ice giants in our solar system, Neptune and Uranus, are both beautiful shades of blue. However, these atmospheres are a different blue than ours. It's caused by the huge amounts of a gas called methane swirling around. (Side note: methane is also the main component of farts.
The blueness of the sky is also affected by other factors, such as the moisture and particulate matter in the air. So tropical countries, such as Singapore or India, which are closer to the equator and are more humid or have pollution or dust in the air, have less blue skies than Australia, most of the time.
If there were no water on earth, would the sky still appear blue? Yes; the scattering of the sun's light is dependent on the optical density of the atmosphere. The shorter wavelengths (ie blue) get scattered more, so we see them out in the sky.
To an astronaut, the sky looks dark and black instead of blue because there is no atmosphere containing air in the outer space to scatter sunlight. So, there is no scattered light to reach our eyes in outer space, therefore the sky looks dark and black there.
The blue color of the sky is a result of this scattering process. At night, when that part of Earth is facing away from the Sun, space looks black because there is no nearby bright source of light, like the Sun, to be scattered.
In space or on the Moon there is no atmosphere to scatter light. The light from the sun travels a straight line without scattering and all the colors stay together. Looking toward the sun we thus see a brilliant white light while looking away we would see only the darkness of empty space.
Space, however, is a vacuum—meaning it's basically empty. Gas molecules in space are too few and far apart to regularly collide with one another. So even when the sun heats them with infrared waves, transferring that heat via conduction isn't possible.
WHAT ARE THE MOST POPULAR COLORS IN THE WORLD? A worldwide survey reveals that blue is the most popular color in 10 countries across four continents.
If we could go back to the period of that first light, we would probably perceive an orange glow similar to firelight. Over the next several hundred million years the faint orange glow would fade and redden as the universe continued to expand and cool. Eventually, the universe would fade to black.
Researchers have long regarded color opponency to be hardwired in the brain, completely forbidding perception of reddish green or yellowish blue. Under special circumstances, though, people can see the “forbidden” colors, suggesting that color opponency in the brain has a softwired stage that can be disabled.
Since, only wealthy rulers could afford to buy and wear the colour, it became associated with the royal classes. Purple in the Elizabethan era (1558–1603), under Sumptuary law, enforced by Queen Elizabeth I, purple fabrics are forbidden for all the classes of people except the royal family.
Therefore, the colours 'blueish-yellow' and 'greenish-red' are the alleged “impossible” colours that we can't see.
Nitrogen and oxygen make up most of the molecules in our atmosphere, but any gas or aerosol suspended in the air will scatter rays of sunlight into separate wavelengths of light. Consequently, when there are more aerosols in the atmosphere, more sunlight is scattered, resulting in more colorful skies.
During the blue "hour", red light passes through space while blue light is scattered in the atmosphere, and thus reaches Earth's surface. Blue hour usually lasts about 20–96 minutes right after sunset and right before sunrise. Time of year, location, and air quality all have an impact on the exact timing of blue hour.
Then the universe expanded and the color of the light changed the same way as the color of an incandescent piece of hot iron changes when the iron cools down, until it stops glowing. Before it was black, the sky used to be bright red.