James Webb Telescope Spots Evidence of Plankton Living on Alien Ocean Planet

12.09.2023 - 16:36 / pcmag.com / James

NASA’s James Webb Space Telescope has spotted evidence of potential life on a hydrogen-rich ocean planet based 120 light-years away. 

The planet is called K2-18 b and it orbits a dwarf star in the so-called “habitable zone,” a distance where conditions might be right for life to exist. The space telescope recently analyzed the light emitted from the planet to discern its chemical composition. 

According to NASA, the findings reveal the presence of “carbon-bearing molecules including methane and carbon dioxide,” which are all building blocks to life on our own planet. In addition, the telescope may have detected the presence of a molecule called dimethyl sulfide (DMS) in the planet’s atmosphere. 

“On Earth, this is only produced by life. The bulk of the DMS in Earth’s atmosphere is emitted from phytoplankton in marine environments,” NASA noted. 

The space agency will need to observe K2-18 b more to validate the findings. But if true, it could mean a plankton-like organism—which on Earth act as a crucial food source for other marine life—is present on the alien world. 

However, K2-18 b is quite different from Earth. To start, it's about 8.6 times larger. The data from the James Webb Space telescope also suggests K2-18 b is a hydrogen-rich world covered with an ocean surface, making it a “Hycean exoplanet.” That said, it’s possible the planet’s surface is too hot for life, or for it to sustain a liquid ocean, NASA added. 

“The planet's large size — with a radius 2.6 times the radius of Earth — means that the planet’s interior likely contains a large mantle of high-pressure ice, like Neptune, but with a thinner hydrogen-rich atmosphere and an ocean surface,” the space agency said. (In contrast, Earth's atmosphere is made up mostly of nitrogen and oxygen.)

The space telescope was able to discern the planet’s chemical composition by taking a spectrum, which involves dissecting the emitted light from K2-18 b’s atmosphere. Although other telescopes have taken spectrums of K2-18 b before, James Webb features more powerful sensors, which allowed astronomers to gather more data of the planet’s atmosphere. 

"These results are the product of just two observations of K2-18 b, with many more on the way,” University of Cambridge astronomer Savvas Constantinou told NASA. “This means our work here is but an early demonstration of what Webb can observe in habitable-zone exoplanets.”

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