Forget Mars, are there aliens on… K2-18b? Discovery of planet twice as big as Earth emitting gas 'only produced by life' sparks huge excitement among astronomers

Astronomers could yet show that alien life does beryllium connected a distant satellite pursuing observations today. 

Planet K2-18b – which is much than doubly arsenic large arsenic Earth and 120 light-years distant – sits wrong nan habitable area of its prima successful nan Leo constellation.  

Scientists said past twelvemonth they thought they'd detected dimethyl sulphide state successful its atmosphere – a compound that is 'only produced by life'.

Now, to corroborate nan finding, nan James Webb Space Telescope will undertake hours of observations of nan satellite connected Friday.  

However, abstraction fans will person to hold respective months for nan results to beryllium authenticated and published.

Investigations of satellite K2-18b are being led by Dr Nikku Madhusudhan, an astrophysicist astatine nan University of Cambridge. 

He's called it a 'hycean' world – a comparatively caller word he coined for a rocky satellite pinch a hydrogen-rich ambiance and oceans of water.

'If we do observe DMS [on K2-18b] it does put it fundamentally astatine nan apical for imaginable signs of habitability,' he told the Times. 

K2-18b – much than 8 times nan wide of Earth and complete doubly arsenic large – was discovered successful 2015.

But it was only successful 2019 that the beingness of h2o vapour successful K2-18b's atmosphere was reported. 

Then, past year, nan James Webb scope detected c dioxide and methane in its atmosphere, arsenic good arsenic a shortage of ammonia.

Dr Madhusudhan called this a 'very profound moment' because it supports nan mentation that there's a h2o water underneath a hydrogen-rich atmosphere.

But it was nan beingness of thing other that sewage astronomers moreover much excited. 

Initial Webb observations provided a imaginable discovery of a molecule called dimethyl sulfide (DMS), which connected Earth is 'only produced by life'. 

The bulk of nan DMS successful Earth’s ambiance is emitted from phytoplankton successful marine environments – suggesting a akin shape of life connected nan distant planet.

In fact, scientists person been incapable to deliberation of immoderate earthy geological aliases chemic process that could create DMS without surviving organisms. 

Dr Madhusudhan said nan uncovering was a daze but because they were first observations he could only opportunity pinch 50 per cent assurance location is DMS on K2-18b. 

'It was a existent shock, I had sleepless nights for a week,' he added.

'That week, I didn’t moreover muster nan courageousness to break it to my ain team.'  

Today, 8 hours of observations by nan James Webb scope should supply a definitive reply – though nan master will person to walk months poring complete nan information to get it.

NASA's $10 cardinal (£7.4 billion) observatory is capable to analyse the chemical make-up of a distant satellite by capturing nan ray from its big prima aft it has passed done nan planet's ambiance connected its measurement to Earth. 

Gases successful nan ambiance sorb immoderate of nan starlight but each time off tell-tale signatures successful the spectrum of light that astronomers tin past unpick. 

Although Hycean worlds are predicted to beryllium covered successful water, researchers opportunity it is besides imaginable that K2-18 b's hypothesised water is excessively basking to beryllium habitable aliases beryllium liquid. 

In fact, a study published earlier this twelvemonth suggested nan water whitethorn beryllium lava. 

K2-18b is known arsenic a 'super Earth' because it is bigger than our satellite but smaller than Neptune. 

K2-18b's ample size – pinch a radius 2.6 times nan radius of Earth – intends that nan planet's interior apt contains a ample mantle of high-pressure ice, for illustration Neptune, but pinch a thinner hydrogen-rich ambiance and an water surface. 

'Although this benignant of satellite does not beryllium successful our star system, sub-Neptunes are nan astir communal type of satellite known truthful acold successful nan galaxy,' said interrogator Subhajit Sarkar of Cardiff University. 

'We person obtained nan astir elaborate spectrum of a habitable-zone sub-Neptune to date, and this allowed america to activity retired nan molecules that beryllium successful its atmosphere.'