Earth wasn’t always the same color according to scientists: This might be what our planet looked like millions of years ago
Here’s how some scientists believe the Earth looked millions of years ago.
While it may seem crazy, the idea that millions of years ago the Earth looked purple is gaining traction. Yes, you read that right, aliens might well have known us as ‘The Purple Planet’.
The idea, known rather handily as the Purple Earth hypothesis, suggests that single-celled organisms needed a much less complex molecule than chlorophyll to utilise sunlight in their daily lives.
Astrobiologist Dr. Edward Schwieterman of the University of California, Riverside, and professor Shiladitya DasSarma of the University of Maryland have led the study that says retinal was the pivotal molecule in their construction, something which would have given them a bright shade of violet.
Some biologists believe that early Earth was not (largely) blue and green but blue and purple. Earth might have looked something like this.
— Quite Interesting (@qikipedia) July 26, 2023
Image: Oleg Kuznetsov; CC BY-SA pic.twitter.com/nJXnwSToYz
Chlorophyll, as we were all incessantly told by our high-school teachers, is the powerhouse of the cell and the key component in photosynthesis – the process that lets plants turn sunlight into energy.
The pigment is the first step in producing the oxygen that we need to live. Importantly in the colour discussion, chlorophyll mostly absorbs light from the blue and red spectrum while reflecting green, which is why leaves look green to our eyes.
However, chlorophyll was not the first photosynthesising formula on the planet. In the early years, retinal, a much simpler molecule, was likely present when atmospheric oxygen was not easy to come by. Over time, these primeval structures would evolve into what we see today, but millions of years ago, things had to survive in more hostile conditions, and retinal can do just that.
For example, as put by earth.com, halobacterium, “a bright purple microbe that uses retinal and survives in salty spots like the Great Salt Lake, absorbs green wavelengths through retinal and reflects red and blue, making it look purple.”
There is a theory that billions of years ago plants used the molecule retinal instead of chlorophyll, which would make all plant life on Earth appear purple instead of green.
— Quite Interesting (@qikipedia) November 28, 2020
So now you know. When the aliens come and ask us why nothing’s purple anymore, you can tell them.
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