It is believed that there can be no life on distant exoplanets because their stars emit too much UV radiation. However, scientists have found that in ancient times the young Earth received much larger doses of radiation - and yet gave birth to living organisms.
We are surrounded by alien worlds. In nearby star systems, there are many Earth-like planets with unusual names: Proxima b, TRAPPIST-1e, Ross-128b and LHS-1140b. Are these mysterious planets inhabited? What amazing life forms can they inhabit?
If earlier scientists were optimistic, now their aspirations are almost completely dispelled under the pressure of new facts. Although all these planets are located inside the so-called "Goldilocks zone" - that is, at such a distance from the star that stable liquid water can exist on the planet's surface - there is one delicate circumstance.
Hell fire
Of course, this is just a metaphor. In fact, we are talking about incredibly strong solar radiation. Planets orbiting M-type stars (the so-called "red dwarfs") are regularly exposed to powerful solar flares that can completely destroy the potential biosphere. However, a new study by astronomers from Cornell University demonstrates that even in such harsh conditions, the protein life we are used to can still exist.
To understand how this is possible, first you need to take a good look at the planet known to us in the Goldilocks zone, the existence of life on which does not require proof - to the Earth. Astronomer Jack O'Malley-James, along with colleague Lisa Kaltenegger, modeled the flow of ultraviolet radiation regularly irradiating potentially habitable planets (Proxima b, TRAPPIST-1e, Ross-128b and LHS-1140b) and compared it to the radiation that the Earth is exposed to.
In the simulations, the scientists looked at a number of different atmospheric compositions, since denser atmospheres are more effective at protecting surfaces from the harmful effects of UV radiation than thin (eroded or oxygen-free) atmospheres. Now the earth's atmosphere is doing its job very successfully, but this was not always the case. It turned out that compared to the young, newly formed Earth, exoplanets are less irradiated - although such a dose seems extremely high to modern man.
Promotional video:
Despite this circumstance, life was still able to arise and develop even in extreme conditions. In this regard, the researchers conclude that, despite the powerful streams of ultraviolet radiation, life has all the chances of originating on distant planets. “Although the oxygen-free atmosphere of exoplanets allows radiation to do much more harm to organic matter, things were even worse on our Earth in the distant past. Thus, the high level of surface radiation does not exclude the possibility of life emerging,”the authors explain in their article.
This instills a certain optimism in the hearts of all scientists interested in the search for extraterrestrial life. Many are even convinced that a high level of radiation is one of the key factors in the emergence of life as such, and it is only for the benefit of hypothetical organisms. Perhaps we too early gave up the opportunity to meet our fellows in distant space?
Vasily Makarov