K2-18b

21.04.2025

K2-18b

Why in the news?                        

In 2025, scientists detected the presence of either dimethyl sulphide (DMS) or dimethyl disulphide (DMDS) in the atmosphere of K2-18b.

What is K2-18b?

• K2-18b is an exoplanet (a planet located outside our solar system) situated 124 light-years away from Earth in the constellation Leo, orbiting a star called K2-18.
• It was discovered in 2015 by the Kepler Space Telescope.
• K2-18b is 5.2 times wider and around 9 times more massive than Earth, suggesting it may possess a hydrogen-rich atmosphere.
• The planet receives a similar level of stellar radiation from its star as Earth does from the Sun, hinting at the possibility of habitable surface conditions.

Atmospheric Discoveries:

• In 2019, the Hubble Space Telescope detected water vapour in the atmosphere of K2-18b.
• Later, the James Webb Space Telescope (JWST) found the presence of carbon dioxide (CO₂) and methane (CH₄).
• The absence of ammonia along with CO₂ and CH₄ in a hydrogen-rich atmosphere is significant because it may indicate the possible presence of a liquid water ocean.

About Dimethyl Sulphide (DMS):

• DMS is considered a potential biomarker because, on Earth, it is mostly produced by phytoplankton in the oceans.
• DMS is formed when phytoplankton die and enzymes break down dimethylsulphoniopropionate (DMSP).
• It is also released when soil bacteria decompose plant matter and in trace amounts during volcanic eruptions.
• A 2015 study found that 76% of soil bacteria on Earth contain a gene that produces DMS, reinforcing its biological origin.

                                  Source: Indian Express

Consider the following statement regarding to the K2-18b:

1.K2-18b is an exoplanet (a planet located outside our solar system) situated 124 light-years away from Earth.

2.It was discovered in 2015 by the Kepler Space Telescope.

Which of the statements given above is/are correct?

A.1 only

B.2 only

C.Both 1 and 2

D.Neither 1 nor 2

Answer C