K2-18b: Another Planet Earth

Planet Earth may have some competition.

Molecules resembling those produced by simple life on Earth have been found on the exoplanet K2-18b.

The research, conducted by a Cambridge team, was found through NASA's James Webb Space Telescope (JWST) and showed the scientists and astronomers’ data on the planet's atmosphere.

However, they have said that more data needs to be collected to fully confirm the results of life on another planet.  

The Cambridge group found that K2-18b has at least one of two chemicals in its atmosphere, which signal to associations of life: dimethyl sulphide and dimethyl disulphide. These are gases produced by marine phytoplankton and bacteria on Earth. 

Professor Madhusudhan at Cambridge University mentioned to the BBC that he was surprised by the sheer volume of these gases in K2-18b’s atmosphere. He said the planet should be ‘teaming with life’ as it has a higher quantity of the dimethyl sulphide and dimethyl disulphide gases than Earth does. 

K2-18b is 120 light-years away from Earth and much larger in size - 2.6 times the radius of Earth. Therefore, the planet's interior could resemble Neptune’s with a large mantle of high-pressure ice and a thinner layer of the hydrogen-rich atmosphere and ocean. 

However, K2-18b and Neptune are unlikely to have the oceans we find on Earth. They may even be uninhabitable due to extremely hot ocean temperatures for animals to survive in, or simply the water evaporating.

K2-18b could now be classed as an Hycean exoplanet - a planet featuring a hydrogen rich atmosphere and a water-covered surface. More research must be done to confirm this.

NASA has said that the team will be conducting follow-up research using a Mid-Infrared Instrument. This is a space telescope for finding wavelengths undetectable to the naked eye. The hope is that NASA will be able to further analyse the environmental conditions on K2-18b.