Ruminations: Here Comes the Sun!

"The sun would appear green if your eyes could handle looking at it."
"Basically, when you look at the sun, it has enough of all the different colours in it and it's so bright that everybody's eyes are firing like crazy and saying, 'It's too bright for me to tell you what colour it is'."
"That's why the sun looks white to us."
"Essentially, it's a green star that looks white because it's too bright, and it can also appear yellow, orange or red because of how our atmosphere works."
"The sun is at its mid-life, and it still has quite a lot of years before it changes colours. It still hasn't dimmed out one bit."
"When astronomers say colour, they really mean temperature. But to anyone in the public, colour just means the colour you see and how you make sense of the world."
W. Dean Pesnell, project scientist, Solar Dynamic Observatory, NASA

"We think of perception and vision as being really straightforward, with this idea of 'I have my eyes and see'. And, actually, it's not like that at all. It's influenced by where you grow up, when you grow up and who you grow up around."
"When you're a kid, you don't necessarily pay that much attention to these deep philosophical questions about the nature of colour and light in the way you might start to when you're sitting in your office looking out the window on a sunny day, so perhaps you just override your memory with the learned association of 'yellow equals sun', which you leaned on heavily as a child."
"This is just another neat example of how life paints colour."
Alice Skelton, researcher of developmental colour science, University of Sussex, Britain

Do you know what color the sun really is? solarsystem.nasa.gov

While children in Japan might colour a circle red to represent the sun, in alignment with their national flag [Land of the Rising Sun], those in North American have a tendency to sketch a yellow circle. Adults are now debating the colour of the star at the centre of our solar system, some of whom feel it has changed hues since the time of their childhood. Weeks back, writer Jacqui Deevoy tweeted her opinion that the round yellow sun of her childhood had turned white and looks wonky. Her post amassed 6 million views.

Some of those had responses with people either agreeing with Deevoy's observation or those who claimed the sun had always appeared white. And as far as science is concerned, it's neither -- while being a bit of both. The sun from its 150 million kilometre distance generally appears a white spot in the sky, while the yellow tint perceived by some people is related to how light is scattered. Molecules in the air redirect sunlight's blue and violet wavelengths, and this directs more yellow and red to meet our eyes.

Sunlight passes through a thicker atmosphere as day transforms into night, so more molecules scatter its blue hues and lead to displays of oranges and reds at sunset. The sun's hue is really light bouncing off surfaces. With stars, colour equals temperature; the hotter a star, the more blue light it gives off. Cooler stars appear red. The sun at its core has a temperature topping 15 million degrees Celsius; "somewhere in the middle, in this weird space where we can't perceive its colour", observed Dr. Pesnell. In the distant future the sun is expected to change hues.

The sun appears different depending on who’s looking. From left, NASA’s NuSTAR sees high-energy X-rays; the Japanese Aerospace Exploration Agency’s Hinode mission sees lower energy X-rays; and NASA’s Solar Dynamics Observatory sees ultraviolet light. NASA/JPL-Caltech/JAXA

The source of all the light and heat that makes flowers bloom, birds sing and people smile emanates as a result of the conversion of hydrogen to helium taking place deep inside the sun's core. The hydrogen gas will -- in a vast stretch of time run out. The sun will enlarge exponentially and take on a deep red shade then ingest all the planets surrounding it and finally it will glow bright blue for a while, and then dim to such a low temperature its colour will become imperceptible ... but no one will be around by then to perceive it.

That colossal event won't take place for at least four billion to five billion years into the future. The sun has some people convinced it has become whiter, but this is connected with the brain's perception more than with astrophysics, according to Dr. Pesnell. Perception itself differs from person to person. Colour, in its most physical sense is what people see when a wave length enters the eye and specialized cells send signals to the brain which translates waves into the colours we see. Everyone may be receiving the same information, but individual life experiences and backgrounds dictate what we make of it.

In the Arctic Circle for example, where some children are born during its long periods of darkness and others experience prolonged sunlight, colour looks different, depending on those life-beginning circumstances. As adults, research shows time of birth influences abilities to distinguish different shades. Language and culture may also play a role, with some not having a specific word to differentiate between blue and green, as an example. Dr. Skelton points out that people's upbringing and how they learn to associate colours with objects can affect perception.