Scientists have found a new way of finding oxygen on distant planets that could help them discover alien life.

The technique could be used by Nasa's James Webb Space Telescope to sniff oxygen on planets in distant solar systems.

That in turn could help discover planets that are alive, and could be home to extraterrestrial life.

One of the possible indicators of life on other planets is oxygen in its atmosphere. On Earth, oxygen is created when living organisms convert sunlight into chemical energy – and scientists think the same might happen on Earth.

Now scientists hope that the new technique could allow them to spot the same signal coming from other planets, and in so doing perhaps spot planets that might be home to alien life.

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The breakthrough, described in a new paper published in Nature Astronomy, allows Nasa's telescope to detect one of the signals that comes from oxygen molecules when they collide with each other. As they do, they block out a specific part of the infrared spectrum, and the new telescope will be able to see that and give scientists a clue to the distant worlds' atmosphere.

Technology like the James Webb Space Telescope is the best hope for examining such distant planets, since they are too far away to ever visit or even to see in much detail, but it requires incredible advanced technology because of the weakness of the signals.

"Before our work, oxygen at similar levels as on Earth was thought to be undetectable with Webb," Thomas Fauchez, from NASA's Goddard Space Flight Center and lead author of the study, said in a statement.

"This oxygen signal is known since the early 1980s from Earth's atmospheric studies but has never been studied for exoplanet research."