Is there anybody OUT THERE?
If life does exist on exoplanets, its fingerprints could be discovered in the light from distant stars
It’s the million-dollar question that astronomers – and biologists – are trying to answer. We now know that planets are plentiful and that the simple carbon-bearing building blocks of life can be found all across interstellar space. But so far, Earth is the only planet known to harbour living organisms. And although many exoplanets orbit in the habitable zone of their parent stars, being habitable isn’t quite the same as being inhabited.
During a transit, however, a tiny amount of starlight passes through the planet’s atmosphere before reaching Earth. Atmospheric molecules leave telltale spectroscopic ‘fingerprints’ in the light of the parent star, mainly at infrared wavelengths. Future giant ground-based telescopes, as well as NASA’s James Webb Space Telescope (JWST), due to launch in the spring of 2019, will be able to detect these so-called biomarkers – chemical compounds such as oxygen, ozone and methane – that are most likely to be produced by biological activity on the planet’s surface.
“TESS will deliver the observational targets for JWST,” says Dr Elisa Quintana of NASA’s Goddard Space Flight Center. Whether the million-dollar question will be answered any time soon, however, is anybody’s guess.