Shining (star)light on the search for life

In the hunt for life on other worlds, astronomers scour over planets that are light-years away. They need ways to identify life from afar—but what counts as good evidence?

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> but what counts as good evidence?

Well, for starters, a planet that is more than 0.7 AU from its parent star.

Which rules out every planet found by doppler methods, every planet found by Kepler, and every planet that will be found by Tess.

mollwollfumble said:

> but what counts as good evidence?

Well, for starters, a planet that is more than 0.7 AU from its parent star.

Which rules out every planet found by doppler methods, every planet found by Kepler, and every planet that will be found by Tess.

> France points to M-dwarf stars to make this case. Smaller and colder than our Sun, M-dwarfs account for nearly three-quarters of the Milky Way’s stellar population.

We can rule out planets orbiting M dwarfs as well. These are flare stars, extremely variable, emitting huge bursts of deadly UV at irregular intervals.

> UV light also broke up molecules of water vapor, releasing single oxygen atoms. The atmospheres created oxygen—but without life.

Well, duh, you don’t need to leave the solar system for that. Enceladus has an atmosphere of 100% molecular oxygen, generated by UV light from the Sun (yes even that far out) breaking up water molecules.

> SISTINE measures the high-energy radiation from these stars. With knowledge about host stars’ spectra, scientists can better distinguish true biomarkers from false-positives on their orbiting planets.

No.

Dang it, forum shut me out while posting.

Anyway, to summarise.

No such thing as a good biomarker for life as we know it on/in exoplanets.

But good signs that there’s no life as we know it there include gases (such as sulphur) at temperatures above 374 degrees C. And planets so small that they’re frozen solid all the way through.