Our eyes evolved to see in the presence of sunlight, as our circadian clock evolved for us to work during the day.
Criteria: K | The Sun
“Let there be light.”
And light was created, made,
and gifted.
To give us day.
Each new morning.
And a sun set
and rise
To look to.
To marvel at.
If only we could
see it closer.
Feel it closer.
Touch its warmth.
But for now I’ll sit here in the sunshine.
Knowing tomorrow
They’ll be more light.
To marvel at.
To look for.
What is sunlight?
“Sunlight is a portion of the electromagnetic radiation given off by the Sun, especially infrared, visible, and ultraviolet light. On Earth, sunlight is scattered and filtered through Earth’s atmosphere, and is seen as daylight when the Sun is above the horizon.”[1] That’s sunlight. What is the Sun made out of? It’s about 90 percent hydrogen and 9 percent helium, with a trace of heavier elements.[2]
The Sun, the centre of our known universe. A star which is our Sun. A source of light and day. Light and darkness. A reckoning of the Sun — The Sun is a mega energy producer. The heat from the Sun drives our weather and our climates.[3] If you filter down the hierarchy of energy sources, what powers the Earth and gives it strength, solar energy, you come down to the energy sources we humans make use of. Without energy, our lives become highly disrupted due to our dependence on all things electrified and technological. We form part of a highly energy-reliant global society.
This post brings together random aspects of the Sun. My favourite parts being the birth of the Sun, the nuclear fusion taking place at the Sun’s core (the reason it shines), and how our eyes evolved by adapting to the Sun.
Dear Patient Reader,
The power of the Sun to power processes on Earth is larger than us. It is much greater than we may imagine or understand. When we think about the past, present, and future, all of them have included, include, and will include the Sun. The Sun is a constant. Let’s not forget that the Sun is a star. Quite a grand one, that’s for sure. The Sun is Earth’s closest star. Even at a distance of 150 million kilometers (93 million miles), the Sun’s gravitational pull holds the planet in orbit. It radiates light and heat (solar energy) making it possible for there to be life on Earth.[4] We all need sunlight. Plants, animals, and humans. We all need it. Plants photosynthesise and we soak in vitamin D. “Vitamin D is essential to the body as it promotes the absorption of calcium.”[5] That way, the Sun keeps us upright, alert, and working. We bask in its greatness.
“The Sun offers free and clean energy in abundance. In fact, it gives us much more energy than we will ever possibly use.”[6] It gives us day to look forward to and work in. That’s our circadian clock and the Sun at play. They work in tandem. It’s a magnificent, glowing power source. For example, “solar cells are the established power source for satellites, including those used in the telecommunications industry.”[7] You may not have been able to so easily access Facebook if it weren’t for the Sun’s energy. Thank you Sun, we love you.
How old is she? The Sun? It’s about 5 billion years old. The birth of the Sun: “At the time, a giant star in our galaxy ended its life in a cataclysmic supernova explosion. The shockwaves from the explosion compressed the surrounding gases that, as they cooled, formed a cloud containing a mixture of dust and hydrogen atoms and molecules. The cloud contracted over a long period of time under their own gravity, causing them to grow denser and heat up internally. Once the core reached a sufficient temperature (about 10,000,000 degrees Kelvin), nuclear fusion began. Meaning that hydrogen atoms started fusing together to form helium. With the start of nuclear fusion, stars begin emitting massive amounts of energy, making them shine. This is how the Sun was born, and is also the reason why stars like the Sun, which emit their own light, are immense masses of gas in which nuclear fusion is taking place at the core.”[8] Super cool. “It’s thought that the nuclear fusion occurring in the Sun’s core fuses 650 million tons of hydrogen every second, transforming it into helium.”[9] That’s the same weight of grain China harvested for the sixth year in a row in 2020. The enormity of the Sun’s nuclear fusion is baffling. And it’s a reminder to mankind; best not mess with the Sun.
What is the colour of the sunlight that touches our hands? Some of the most endearing instances of the colours of the sun are sunbeams, crepuscular rays. And of course the colours we see in the sky when the sun sets. “Crepuscular rays are beams of sunlight that appear to radiate from the Sun’s position. Shining through openings in the clouds or between other objects like mountains or buildings.”[10] Look out to the distant horizon. Take in what you see. If it’s bricks and buildings then you might just find traces of the Sun through cracks through your curtains or gaps through the door.
“You have undoubtedly noticed that the Sun appears yellow rather than bright red. The kind of light detectable by the human eye is called visible light, which has a wavelength between around 400 to 700 nanometers. The human eye is said to be most sensitive to light in wavelengths around 500 nanometers. The greatest amount of sunlight is emitted at wavelengths around 500 nanometers, so you can easily see why sunlight appears yellow. It is believed that the reason behind this sensitivity is the evolution of the human eye by adaptation to the solar spectrum.” Our eyes see what we evolved to see. The human eye evolved by adapting to the Sun. To have eyes that register the world, is to see everything under the Sun. Everything sunlight touches. The Sun inspires awe. How not to admire its brightness, its incessant light? It’s life-giving luminance.
“Sunny-side up please.” Because life’s better with the Sun.
Have a good week ahead fellas. Ciao
P.S. I can’t leave without making reference to Baby Sun from Teletubbies. That was rather epic to young children in the early 2000s. I was so happy to have a Teletubbies backpack that was almost the size of my body, heading off to nursery school. Oh Teletubbies. Now, in hindsight, it was strange.
P.P.S. Next week’s post is titled “The Mother Goose and Her Tree”, which is about the role hub trees, or mother trees as they are called, play within the mycorrhizal network.
References
[1] https://en.wikipedia.org/wiki/Sunlight
[2] https://www.clearwaycommunitysolar.com/blog/all-about-renewable-power/what-do-we-know-and-not-know-about-the-sun/
[3] "Ibid."
[4] https://www.nationalgeographic.org/article/power-sun/
[5] https://sawellnesscentre.com.au/importance-of-sun-for-humans/
[6] "Ibid." [4]
[7] "Ibid." [4]
[8] https://global.canon/en/technology/s_labo/light/002/01.html
[9] "Ibid."
[10] https://en.wikipedia.org/wiki/Sunbeam
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