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In 2025 astronomers reported that the atmosphere of K2-18b, a planet 124 light-years away, may contain gases that on Earth are made mostly by living things. Other scientists quickly cautioned that the signal is weak and is not proof of life.

University of Cambridge / JWST (2025)

SpaceScience

The story behind the card

The planet is about 8.6 times Earth's mass and orbits a small red star in the zone where liquid water could exist. A Cambridge team led by Nikku Madhusudhan argues it may be a 'hycean' world, an ocean under a hydrogen-rich atmosphere. Using the James Webb Space Telescope, the team reported signs of dimethyl sulfide, a gas made on Earth mainly by marine plankton, but at a statistical strength below what scientists normally require for a discovery. Other groups reanalysed the same data and found the signal weak or absent, and noted that the gas can also form without life. The debate shows how such claims are tested: by checking the data again and again.

Türkçe oku
Gökbilimciler 2025'te, 124 ışık yılı uzaklıktaki K2-18b gezegeninin atmosferinde, Dünya'da çoğunlukla canlıların ürettiği gazların bulunabileceğini bildirdi. Başka bilim insanları hemen uyardı: İşaret zayıf ve yaşamın kanıtı sayılmaz.
Cambridge Üniversitesi / JWST (2025)

K2-18b, Dünya'nın yaklaşık 8,6 katı kütlede bir gezegen; küçük, kızıl bir yıldızın çevresinde, sıvı suyun bulunabileceği kuşakta dolanıyor. Nikku Madhusudhan'ın yönettiği Cambridge ekibine göre burası, hidrojence zengin bir atmosferin altında okyanusla kaplı bir “hycean” dünya olabilir. Ekip, James Webb Uzay Teleskobu'nun verilerinde, Dünya'da daha çok denizdeki planktonların ürettiği dimetil sülfür gazının izlerini gördüğünü açıkladı; ancak sinyalin gücü, bilimde bir keşif için genellikle aranan eşiğin altındaydı. Aynı verileri yeniden inceleyen başka ekipler işareti zayıf buldu ya da hiç bulamadı ve bu gazın canlılar olmadan da oluşabileceğini hatırlattı. Tartışma, böyle iddiaların nasıl sınandığını gösteriyor: verilere tekrar tekrar bakılarak.

Sources and further reading

Background reading: K2-18b
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