1 day Ago By Shane Galvin
Astronomers have discovered a major sign of life — and “the first hints...
of an alien world” on a distant planet orbiting outside the solar system, according to a new report. The scientists believe the exoplanet, K2-18b, is a “Hycean planet” — meaning it’s home to an abundance of a particular molecule that is only produced on Earth by living organisms such as marine algae, according to a new report. K2-18b — which is eight times the size of Earth and 124 light-years away — shows signs of the unique molecule dimethyl sulfide, according to a new study published in the Astrophysical Journal on Wednesday.
“This is a revolutionary moment,” Dr. Nikku Madhusudhan, an astronomer at the University of Cambridge and author of the study, said at a news conference Tuesday, according to NPR . “These are the first hints we are seeing of an alien world that is possibly inhabited,” he claimed.
The organic compound — composed of sulfur, carbon, and hydrogen — is naturally produced by phytoplankton and sometimes in bacteria in beer, and appears en masse over Earth’s oceans. Madhusudhan and his team reported taking atmospheric measurements of the dimethyl sulfide on K2-18b back in 2023 — and confirmed the molecule’s overwhelming presence in tests conducted last year with the James Webb Space Telescope. Those signals from the life-byproduct were so strong that researchers had to work diligently simply to omit their presence while conducting other tests — dimethyl sulfide measured at 1,000 times the levels found on Earth, according to the study.
“It is a shock to the system,” Madhusudhan said at the press event. “We spent an enormous amount of time just trying to get rid of the signal.” K2-18b was already known to contain water vapor and the newly found presence of dimethyl sulfide indicated to researchers something they first predicted in 2021 — that K2-18b is a “Hycean world.
” “Hycean” is a term coined by Dr. Madhusudhan in 2021 for a sub-species of exoplanets called “sub-Neptunes,” that have liquid oceans and have hydrogen-rich atmospheres — which they believed at the time applied to K2-18b. During James Webb readings in 2023, Madhusudhan and his team were able to confirm the presence of several molecules predicted by their “Hycean” theory, including hydrogen, methane, and other carbon components — and also made the initial discovery of dimethyl sulfide.
To get these measurements, scientists use the James Webb Space Telescope to record light from the host star as it is refracted through the planet’s atmosphere as the sub-Neptune passes across the star’s face from Earth’s perspective. Elements within the atmosphere will produce different colors as the planet passes across its native star, indicating to scientists what, if any, atmospheric conditions exist. Despite the undisputed measurements of the life-sustaining elements, some scientists said more information and confirmation are needed before a consensus around life on K2-18b can be confirmed.
“It’s not nothing,” Johns Hopkins University planetary scientist Stephen Schmidt told the New York Times. “It’s a hint. But we cannot conclude it’s habitable yet.
” “Unless we see E.T. waving at us, it’s not going to be a smoking gun,” Christopher Glein, planetary scientist at Southwest Research Institute in San Antonio, told the outlet.
Mans Holmberg, a researcher at the Space Telescope Science Institute, participated in the study and called on astronomers to conduct their own independent analysis of the data, NPR reported. “For looking at things like this, it requires a dedicated community effort,” Holmberg told the outlet. “We should be cautious.
I want that to be front and center. Any claim of life on another planet requires a lot of justification, and I don’t think we’re there yet,” he added. In 2015, K2-18b was first discovered by NASA’s Kepler mission, which determined it was in the “Goldilocks zone” of its home star, meaning temperatures were appropriate for water, which is presumed to be a building block of all life.
K2-18b is about eight times the size of Earth but has a much shorter orbital path, completing a circuit around its host star in just 33 days..
