We may not be alone in the universe: Astronomers find possible alien life on planet

USA Today

17-04-2025

We may not be alone in the universe: Astronomers find possible alien life on planet The discovery was made on a massive exoplanet known as K2-18b that for years has captivated scientists who have considered it among the best potential life-harboring ocean worlds.
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'Strongest evidence yet' of alien life discovered on distant planet
Scientists have detected what may be the strongest evidence of alien life yet on a planet orbiting a star 120 light-years from Earth.
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Data suggests K2-18b is a "world with an ocean that is teeming with life," said study lead author Nikku Madhusudhan, an astrophysicist at the University of Cambridge in England.
A whopping 8.6 times bigger than Earth, K2-18b orbits a red dwarf star in the constellation of Leo in what's known as a habitable zone where water is thought to exist on the surface.
Researchers hope to make additional observations with the James Webb Space Telescope to conclusively prove their findings.
Humanity may be one step closer to finally answering the question of whether we're alone in the cosmos with a definitive, "no."
A team of astronomers said it has found signs of what could be extraterrestrial life on a distant planet located far outside of our own solar system.
But don't go imagining little green aliens with big oblong eyes. Using observations from NASA's James Webb Space Telescope, the researchers were able to find possible hints of molecules that on Earth are signs of living organisms like marine algae.
The discovery was made on a massive exoplanet known as K2-18b that is much larger than Earth but smaller than Neptune. For years, the exoplanet orbiting more than 120 light-years away has captivated scientists who have considered it among the best potential life-harboring ocean worlds.
The latest findings on K2-18b comes from a team of researchers led by Nikku Madhusudhan, an astrophysicist at the University of Cambridge in England. While Madhusudhan stopped short of claiming the findings as a conclusive discovery, he said in a statement that the results serve as the strongest evidence yet that life may exist anywhere else besides Earth.
'Decades from now, we may look back at this point in time and recognize it was when the living universe came within reach,' Madhusudhan said in a statement. 'This could be the tipping point, where suddenly the fundamental question of whether we're alone in the universe is one we're capable of answering.'
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What is K2-18b? Scientists have observed exoplanet for years
The exoplanet known as K2-18b was first discovered in 2015 more than 120 light-years from Earth during NASA's planet-hunting K2 mission.
A whopping 8.6 times bigger than Earth, K2-18b orbits a red dwarf star in the constellation of Leo in what's known as a habitable zone – a region where planets could have water, providing a key ingredient for life to flourish. In a nod to the classic fairy tale, astronomers even refer to these regions as "Goldilocks" zones because conditions have to be just right – neither too hot nor too cold – for water to remain in liquid form and pool on planetary surfaces.
Observations in 2019 with Webb's predecessor, the Hubble Space Telescope, previously indicated that the exoplanet could be a Hycean world covered by ocean water underneath a hydrogen-rich atmosphere.
In September 2023, another investigation with Webb – an advanced telescope launched in 2021 outfitted with a gold-coated mirror and powerful infrared instruments – revealed something more: traces of carbon-bearing molecules in K2-18b's atmosphere, including methane and carbon dioxide.
At the time, the discovery served as the best evidence yet that the exoplanet had the potential to support life.
Astronomers detect hint of life with James Webb Space Telescope
Intrigued, astronomers took another look at Webb's observations.
This time, Madhusudhan and his team used a different instrument outfitted to Webb that allowed the researchers to analyze K2-18b in another wavelength range of light so as not to overlap with the previous observations.
Astronomers can determine the chemical composition of the atmospheres of faraway planets by studying the light from its parent star as the planet passes in front of it as seen from the Earth. During K2-18b's stellar transit, Webb was able to detect some starlight being absorbed into the planet's atmosphere that left clues for astronomers to piece together the gases in the atmosphere.
That's what led the researchers to detect a possible biosignature.
The biosignature came in the form of hints of sulfur-based gases dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) in the atmosphere – both molecules from the same chemical family.
On Earth, the gases are only produced by life, primarily microbial life such as marine phytoplankton, according to the researchers. Though an unknown chemical process could still be the source of these molecules in K2-18b's atmosphere – which were also observed to be much more concentrated than on Earth – the researchers are still encouraged by the results.
"Given everything we know about this planet, a Hycean world with an ocean that is teeming with life is the scenario that best fits the data we have," Madhusudhan said in a statement.
What's next? Researchers want more time studying planet
Finding life on another world would be a monumental discovery, but Madhusudhan isn't getting ahead of himself just yet.
The observations could have occurred by chance or could be the result of previously unknown chemical processes at work on K2-18b. For that reason, the researchers say another 16 to 24 hours of follow-up analysis with Webb could help them reach a more definitive conclusion.
'It's important that we're deeply skeptical of our own results, because it's only by testing and testing again that we will be able to reach the point where we're confident in them,' Madhusudhan said. 'That's how science has to work.'
The team's findings were published April 17 in the Astrophysical Journal Letters.
Eric Lagatta covers breaking and trending news for USA TODAY. Reach him at [e-mail]