The hunt for extraterrestrial life is fundamentally flawed. But there's a fix.

The hunt for extraterrestrial life on distant planets may be operating with a big blind spot.

That's because we aren't accounting for the nature of the light coming from the host star itself when we interpret the chemical signatures of life, or biosignatures, on some of the most promising candidate planets beyond the solar system.

If we don't consider that crucial factor, we could be led on a wild-goose chase across the cosmos.

Despite having discovered thousands of exoplanets , we have not detected convincing evidence of alien life on any of them.

But astronomy is reaching a point where powerful telescopes can zoom in on many more potentially habitable worlds.

Planets that orbit M dwarfs, which are small stars cooler than the sun, are particularly promising targets because they have a unique observation window.

When a planet passes in front of one of these stars, it blocks a relatively large fraction of the star's light, making the planet and its atmosphere easier to detect.

There are also a lot of them.

M dwarfs are the most common type of star in the Milky Way .

However, if we misunderstand how these stars interact with planetary atmospheres, we may misinterpret the significance of observations from some of the most promising planets.

The most-studied biosignatures are methane, oxygen and ozone.

On Earth, these are often produced by biological processes, with ozone acting as an indirect indicator of oxygen.

But even on our home planet, molecules typically associated with life are not unambiguous biological fingerprints .

These molecules can be produced by geological and chemical processes, as well as via atmospheric reactions with light from the sun.