Researchers from the University of Cambridge and the Medical Research Council Laboratory of Molecular Biology have identified a group of exoplanets with the same chemical conditions that may have once allowed life to exist on Earth, according to a new study published in the journal Science Advances.
In the research, the team found that ultraviolet (UV) light sparks a series of chemical reactions that produce the essential building blocks needed to create life.
Using that idea, they then identified multiple planets that both sit inside their star’s habitable zone and get enough UV light from their host star to spark such reactions.
It is those distant worlds where life is most likely be found.
The team began the study by theorizing that cyanide helped life exist on early Earth. They argued that carbon from meteorites slammed into our planet millions of years ago and interacted with nitrogen to create hydrogen cyanide.
The cyanide then rained to the surface, where it reacted with the sun’s UV light and generated the first building blocks for RNA.
After using UV lamps to recreate such reactions in the lab, the team managed to build many of life’s essential elements, including lipids, amino acids, and nucleotides.
From there, researchers ran a series of experiments to see how quickly the mix of UV light, water, and hydrogen cyanide or sulphite ions can create those key building blocks. They then repeated the process without light.
That showed, while stars around the same temperature as our sun are able to create the right amount of light for life’s building blocks, cool stars cannot.
As a result, the team believes the only planets worth searching for life at are ones in the so-called abiogenesis zone — a region where planets get both liquid water and enough light to activate basic chemistry.
“The thing that you know best about any exoplanet system is the star,” lead author Paul Rimmer, an astrochemist at the University of Cambridge, told Space.com. “So, that seemed like a natural thing to start with.”
While only a few known exoplanets sit in that zone, the team hopes future technology will be able to track down more hanging throughout the cosmos.
“This work allows us to narrow down the best places to search for life,” added Rimmer, according to Phys.org. “It brings us just a little bit closer to addressing the question of whether we are alone in the universe.”