On 11 September, a study reported observations of the exoplanet K2-18 b by the James Webb Space Telescope (JWST), the most powerful space telescope ever built. The exoplanet’s spectrum revealed the presence of methane and carbon dioxide, but no ammonia, supporting the hypothesis that there may be a water ocean underneath the hydrogen rich atmosphere of K2-18 b.
However, the finding that created the biggest stir, particularly in the media, was that the exoplanet’s spectrum hinted at the presence of dimethyl sulfide (DMS), a molecule which, on Earth, is only produced by life.
But is it too early to get excited and what further information is required to confirm if there really is life on the exoplanet?
K2-18 b is an exoplanet, 2.6 times the radius of Earth, orbiting the cool dwarf star K2-18 in the habitable zone, a region around a star where water can exist in its liquid state on a planet’s surface. It lies 120 light years from Earth in the constellation Leo.
Exoplanets like K2-18 b – also known as a ‘sub-Neptune’ because it sits between the Earth and Neptune in size – are unlike anything else that exists in our solar system and are challenging to explore because they are often outshone by the glare of their much larger parent stars.