The James Webb Telescope discovers traces of Carbon Dioxide & Methane in an Earth-like planet K2-18b

A promising discovery by NASA’s James Webb Space Telescope revealed the presence of carbon-bearing molecules like methane and carbon dioxide on an Earth-like planet. This is promising because this discovery suggests that K2-18b could potentially be a Hycean exoplanet, one that is a water-covered planet with a hydrogen atmosphere.

Observations by NASA’s Hubble Space Telescope of the atmospheric properties of this exoplanet have prompted further exploration that has changed our understanding of this exoplanet.

This planet orbits around a dwarf star K2-18 in the habitable zone (distance from a star at which liquid could be present at the surface of the planet) and is approximately 120 light years away from earth. Exoplanets like K2-18b have sized between Earth and Neptune which is unlike anything in our solar system. This paucity of similar plants nearby has hindered our understanding of such exoplanets and thereby, the nature of their atmosphere is something that is frequently debated by astronomers.

A spectra of K2-18b obtained by JWST showed the abundance of methane and carbon dioxide, and also the shortage of ammonia which suggests that there is a possibility of water being present underneath this hydrogen-rich atmosphere. Initial observations of this exoplanet have also provided “a possible detection of a molecule called dimethyl sulphide (DMS)”. On earth this molecule is only produced by life that is given out by phytoplankton in marine environments. However, this interference of DMN is less robust and would require more exploration and validation to conclude that DMS is present.

Even though this exoplanet is present in the habitable zone it does not mean that this planet can support life, because this planet’s radius is 2.6 times the radius of earth and that means that the planet’s interior is likely to contain “a large mantle of high pressure” ice with a thinner hydrogen-rich atmosphere and an ocean surface”. Usually Hycean world are known to have oceans of water; however, it is also possible that the ocean can be too hot to be liquid.

A team intends to conduct research with the telescope's MIRI (Mid-Infrared Instrument) spectrograph. The team hopes that further explorations may give us valuable insights to the atmospheric conditions of K2-18b.

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Source: Webb Team. NASA. "Webb Discovers Methane, Carbon Dioxide in Atmosphere of K2-18 b". https://www.nasa.gov/universe/exoplanets/webb-discovers-methane-carbon-dioxide-in-atmosphere-of-k2-18-b/. 11/09/23 [Date accessed: 16/09/23].

Edited by: Ansh Pincha