Webb telescope discovers methane, carbon dioxide on potential ocean planet

Scientists used the Webb telescope to look at a distant exoplanet and found that it contains methane and carbon dioxide. This makes the potential ocean planet a good candidate to look for signs of life on.

By: Science Desk

Kochi | September 12, 2023 01:19 PM IST

3 min read

Illustration of a blue coloured planet with a faint red dwarf star in the background

Artist's impression of what the exoplanet will look like. (NASA)

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Scientists used the James Webb Space Telescope to look into the planet K2-18 b and found the presence of carbon-bearing molecules like methane and carbon dioxide. The planet is 8.6 times as massive as Earth and recent studies have suggested that its surface could be covered with water oceans and that it has a hydrogen-rich atmosphere.

The planet K2-18 b orbits the cool dwarf star K2-18 in the “goldilocks zone: where it gets just enough starlight to have liquid water while not enough to boil it off into vapour. The planet is about 120 light-years away from us in the constellation Leo. Studies suggest that it is a “Hycean planet” — a hypothetical type of planet described as a hot, water-covered planet with a hydrogen atmosphere. Some scientists believe that Hycean planets are excellent candidates to search for evidence of life.

The results of the research have been accepted for publication in the journal Astrophysical Journal Letters, according to NASA.

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“Our findings underscore the importance of considering diverse habitable environments in the search for life elsewhere. Traditionally, the search for life on exoplanets has focused primarily on smaller rocky planets, but the larger Hycean worlds are significantly more conducive to atmospheric observations,” said Nikku Madhusudhan, lead author of the paper, in a press statement.

The researchers believe the abundance of methane and carbon dioxide along with a shortage of ammonia supports the hypothesis that there could be a water ocean hiding under a hydrogen rich atmosphere on the planet. The study also documents a possible detection of a molecule called dimethyl sulphide. On our planet, this is only produced by life. The majority of the dimethyl sulphide on Earth is emitted by phytoplankton in the oceans.

But this inference is not completely robust. ““Upcoming Webb observations should be able to confirm if DMS is indeed present in the atmosphere of K2-18 b at significant levels,” added Madhusudhan.

K2-18b does lie in the habitable zone and it does have carbon-bearing molecules but that does not necessarily mean that it can support life. It has a radius 2.6 times that of Earth and this likely means that it has a large mantle of high-pressure ice.

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