To understand what life-signs astronomers read from a planet, they must first understand the planet’s star. (Credit: NASA/GSFC/C. Meaney/B. Monroe/S. Wiessinger)

When astronomers look for signs of life outside of the solar system, they’re mostly looking for what researchers call biosignatures. These are tell-tale indicators that something is living on another world.

So, while the Search for Extraterrestrial Intelligence (SETI) draws headlines for hunting alien communications like radio w