Strongest Evidence of Alien Life Yet Identified Found 124 Light-Years From Earth

Astronomers announced last Thursday the detection of the most promising signs yet of possible life on a planet outside our Solar System — though some in the scientific community responded with caution.

The planet in question is K2-18b, located 124 light-years away in the constellation Leo. For some time now, researchers have debated whether it could be an ocean world capable of harboring microscopic life.

The discovery was made using the James Webb Space Telescope by a British-American research team, who found traces of two chemical compounds in the planet’s atmosphere that have long been considered potential indicators of extraterrestrial life.

Living organisms on Earth, mainly marine microalgae known as phytoplankton, produce these compounds — dimethyl sulfide (DMS) and dimethyl disulfide.

Despite the excitement, the scientists involved urged caution.The researchers emphasized that they need to conduct more observations to confirm the findings — in other words, they have not made a definitive discovery yet.

Still, the implications are significant, according to astrophysicist Nikku Madhusudhan from the University of Cambridge, lead author of the study published in The Astrophysical Journal Letters:
He said during a press conference, We’re now seeing hints of possible biological activity beyond our solar system.
Honestly, I think this is the closest we’ve ever come to identifying something we could attribute to life.

Intriguing Chemical Signs

K2-18b has about eight times the mass of Earth and is 2.5 times larger. It orbits its star in a so-called “habitable zone” — not too hot, not too cold — where liquid water, considered essential for life, could exist.

To study planets this distant, astronomers observe them as they pass in front of their stars, allowing them to analyze how certain molecules block light, revealing atmospheric composition.

In 2023, scientists using the Webb telescope detected methane and carbon dioxide in K2-18b’s atmosphere — marking the first time they found carbon-based molecules on a planet in the habitable zone.

At the time, researchers also detected weak traces of DMS, which prompted them to point Webb back at the planet the following year, this time using its mid-infrared instrument to observe different wavelengths of light.

This second round of observations revealed much stronger chemical signals — though still below the “five sigma” statistical threshold required for a scientific confirmation.

Even if verified, these findings wouldn’t necessarily mean life exists on the planet.

Scientists discovered DMS on a comet last year, suggesting that non-biological processes can produce the compound.
However, Madhusudhan noted that the concentration detected on K2-18b appears to be thousands of times higher than on Earth, which strongly suggests a biological origin.

Are We Alone in the Universe?

Scientists have long considered K2-18b a prime candidate for what’s known as a Hycean planet an ocean world larger than Earth with a hydrogen-rich atmosphere.

Scientists do not expect these types of planets to support intelligent life, but they believe such worlds could host simple microbes similar to those that thrived in Earth’s oceans billions of years ago.

Still, some researchers question whether such Hycean planets — including K2-18b — are actually too close to their stars to maintain liquid water. K2-18b completes one orbit every 33 days.

Raymond Pierrehumbert, a planetary physics professor at the University of Oxford, has conducted separate research suggesting K2-18b is too hot to be habitable.
“If there is water there, it would be hellishly hot and uninhabitable,” he told AFP, adding that oceans of lava are a more plausible scenario.

Sara Seager, a planetary science professor at MIT, urged patience, recalling previous claims of water vapor in K2-18b’s atmosphere that turned out to be a different gas.
She also pointed out that celestial bodies within our own Solar System — such as Mars, Venus, or moons like Saturn’s Enceladus — have a better chance of hosting life.

Madhusudhan estimated that confirming the current findings would require only 16 to 24 more hours of Webb observation, which could happen in the coming years.

He believes that Webb and next-generation telescopes will help humanity detect alien life sooner than many expect. “This could mark the turning point — the moment when we can finally answer the fundamental question: Are we alone in the universe?” he concluded.

Read the original article on: Science Alert

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