I’ve Googled and every source I come across just says “plants gather (light) energy from the sun and use it for photosynthesis.” What exactly is “light energy”? Is is some sort of radiation? Is it just heat?
In: Planetary Science
The energy from the sun reaches us as electromagnetic radiation in the form of photons. Photons can be visible light but also everything from radio waves to x-rays.
The part of the spectrum where the sun emits the most energy that reaches earth happens to be the part we decided to use for seeing.
Evolution has let us use the colors of light that the sun shines the brightest in to see.
Plants also mainly absorb photons (light) in the visible spectrum, because that is where the most energy is to be had.
To be more specific the absorb light that is blue (between 400 and 500 nm in wavelength) and red (around 600 to 700 nm).
There are different types of chlorophyll that do the absorbing with chlorophyll a more towards the edges of the spectrum and chlorophyll b more towards the center, but both lead a gap in the middle where the color green (495–570 nm) is, which is why leaves appear green, they reflect the part of the light they don’t use back at you.
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