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Earth's Strange Red Glow - Chlorophyll Fluorescence

As a satellite revolves around Earth, a keen observation is made… the Earth is glowing red! The red light isn’t emitted from a high population area, so it is clearly not human-made. Astoundingly enough though, a high concentration of red glow is coming from an area with dense plants and vegetation.

Dialing back a couple decades, in 1931 a scientist, Hans Kautsky published a paper on something called the “Kautsky effect” about chlorophyll fluorescence (the mysterious red glow). Through a series of experiments, he moreover noticed the red glow emitted from plants. Now let’s take a look at how this phenomenon takes place.


The Process

When plants absorb sunlight, it goes through a series of different processes and for different reasons, not just making food. There are 3 ways that light is used during photosynthesis:


When plants absorb sunlight, it goes through a series of different processes and for different reasons, not just making food. There are 3 ways that light is used during photosynthesis:


1. Sunlight reaches the chloroplast in the plant which contains chlorophyll pigments. Once the light hits the molecules of the plant it will go through a biochemical process known as photosynthesis and create glucose as energy for the survival of the plant.

2. In cold, wintery places where plants are exposed to a lot of sunlight, but don’t photosynthesize at their regular rate, they need a way to use that extra light energy, or else the plants’ mechanism will be damaged. So in this case, they do what’s best for them by utilizing the light and converting it into heat energy.


3. The third way plants deal with excess light is by radiating it back out, but there’s a catch… they don’t radiate it back exactly how it came in. They simply radiate it back at a different wavelength. According to physics, light has different wavelengths which causes it to appear in different colors. In this case the color is red.


How does this happen?

While photosynthesis is taking place, the original light entering the plant excites the electrons of the chlorophyll molecules. As it goes through a progression of biochemical reactions, some electrons return back to their normal state this way they release energy in the form of light. The light is on the red side of the spectrum, and this is known as chlorophyll fluorescence.


Why can’t we see it ?

Humans are unable to see this red glow, because only 1% of the light that enters is re-emitted into the environment. This amount is too small for the naked eye to notice.


This is a substantial and significant breakthrough for the scientific community, as they now have a more reliable and fastidious device to measure living ecosystems.




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