Photosynthesis is one of the most important chemical reactions to life on Earth. Using it, plants produce carbohydrates, energy absorbed from light, to combine carbon dioxide and water into more complex organic molecules. Oxygen is a side reaction of this process, but it is necessary for our existence. Thanks to photosynthesis, 20 per cent of it is made up of Earth's atmosphere. No photosynthesis, no life on Earth as we know it.
Basics of Life
Most plants use chlorophyll as part of the photosynthesis process. It reflects green light that absorbs red and blue. And that's even though the sun's most intense light is in the green part of the spectrum. It's all about a chemical known as the retinal. It absorbs green color and reflects red and blue. If plants used retinal instead of chlorophyll, most plants would be purple.
Some bacteria use it, but it turns out that chlorophyll is more effective for sunlight; perhaps early life users used a retinal, which is a simpler molecule before understanding how to use chlorophyll.
What's the problem?
Photosynthesis is ideal for a planet that revolves around a bright yellow star, like our Sun, which emits most of the light in the visible spectrum, but such stars make up less than 8% of the stars in the main sequence in our galaxy, but red dwarfs make 75% of the stars in the main sequence.
The problem is that, according to statistics, the vast majority of potentially inhabited planets revolve around such stars, and the red dwarfs are much smaller and colder than our sun. Most of the light they emit is in the infrared range. It's nice and warm, but does it give the impulse necessary for photosynthesis? That's exactly what scientists have been trying to figure out.
What did scientists do?
This is a array of LEDs that simulate the spectrum of the red dwarf. In general, the device can show the spectrum of different types of stars. But the red dwarfs are so common that they were first explored.
Then, in laboratory conditions, scientists created an atmosphere that could be typical of an early inhabited world, added some bacteria, and highlighted it with a modeled starlight.
How was the experiment?
For the experiment, scientists used cyanobacteria to select the sex on them because they are one of the first species on Earth to use photosynthesis to produce oxygen, and they are particularly good for survival under harsh conditions.
It turns out that cyanobacteria flourished and grew under the infrared radiation of a red dwarf, so scientists "complicated" the problem and repeated the experiment with red and green algae.
Thus, despite the fact that the red dwarfs do not emit the kind of light that controlled the evolution of photosynthesis, the earth's organisms could live under the light of the red dwarf.
What's all this about?
The research results are great news for scientists who are looking for extraterrestrial life, and maybe the red dwarfs aren't so hopeless.
However, there are other problems with these stars, which "all spoils." The red dwarfs produce powerful flashes that can destroy the planet's atmosphere in the vicinity. They may eventually lose the basic resources needed for complex organisms. And yet, the authors of the study are optimistic that their research sheds light on our understanding of life on other planets.