Exoplanets are too far away to travel to, but may hold the answers to whether there is other life in the universe.
Now scientists have developed a new method to detect oxygen in the atmospheres of the distant bodies.
They believe it may help accelerate the search for life.
One possible indication of life, or biosignature, is the presence of oxygen in an exoplanet’s atmosphere.
On Earth, it is generated when organisms such as plants, algae, and cyanobacteria use photosynthesis to convert sunlight into chemical energy.
The new technique will see researchers use Nasa’s James Webb Space Telescope to detect a strong signal that oxygen molecules produce when they collide.
This signal could help scientists distinguish between living and nonliving planets.
Thomas Fauchez, of Nasa’s Goddard Space Flight Centre, and lead author of the study, said: “Before our work, oxygen at similar levels as on Earth was thought to be undetectable with Webb.
“This oxygen signal is known since the early 1980s from Earth’s atmospheric studies but has never been studied for exoplanet research.”
University of California Riverside astrobiologist Edward Schwieterman originally proposed a similar way of detecting high concentrations of oxygen from nonliving processes and was a member of the team that developed this technique.
The work has been published in the journal Nature Astronomy.
Dr Schwieterman said: “Oxygen is one of the most exciting molecules to detect because of its link with life, but we don’t know if life is the only cause of oxygen in an atmosphere.
“This technique will allow us to find oxygen in planets both living and dead.”
When oxygen molecules collide, they block parts of the infrared light spectrum from being seen by a telescope.
The scientists say that by examining patterns in that light, they can determine the composition of the planet’s atmosphere.
However, they state that an abundance of oxygen on an exoplanet may not necessarily mean abundant life.
It may instead indicate a history of water loss caused by the planet being too close to its star, leading to the evaporation of oceans.
Dr Schwieterman cautions that astronomers are not yet sure how widespread this process may be on exoplanets.
“It is important to know whether and how much dead planets generate atmospheric oxygen, so that we can better recognise when a planet is alive or not,” he said.