Master student looks for alien life
This is how we’ll find a second earth
Over the past few years, astronomers have found approximately four thousand exoplanets that revolve around stars other than our sun. Every time, people wonder: is this where we’ll finally find alien life? Might we not be alone in the universe?
These planets need to meet a few criteria, though. A ‘second earth’ cannot be too far away from its sun, nor too close, ‘enabling earth-like temperatures that lead to liquid water’, Oosterloo explains. They need a stable surface; gas giants like Jupiter cannot sustain life. They also need a carbon cycle. In a carbon cycle, rock on the surface absorbs CO2 from the atmosphere, which is then recycled through tectonic plates and volcanoes.
‘Carbon cycles stabilise temperatures’, says Oosterloo. ‘This ensured the liveability of earth, when the sun has increased in brightness by 20 percent over the past few billion years.’
Which of these four thousand exoplanets meets these requirements? We have no idea. They’re simply too far away for us to know what’s happening on the surface.
Oosterloo and his supervisors came up with a workaround. ‘We know the mass and radius of these planets’, he explains. ‘By using our knowledge of the carbon cycle here on earth, we can extrapolate what that would look like on planets with a different mass and radius.’ They developed a model that allows them to predict how much CO2 there is in a planet’s atmosphere.
It doesn’t help us much just yet, but that is changing, says Oosterloo. ‘The launch of the James Webb telescope will lead to a wealth of information on what the atmosphere on the exoplanets we know is made of.’ This will enable astronomers to figure out whether these exoplanets have a carbon cycle and whether they might sustain life.
There is currently one good candidate, says Oosterloo, who’s since started his PhD track. Exoplanet Kepler 452b, discovered in 2015. But, he emphasises: ‘We’ll discover many more exoplanets in the future, including around small stars where we currently can’t see any planets.’