Some molecules are unstable and unlikely to be in high concentrations but also leave obvious spectra (like O2, O3, CH4). You can tell by atmospheric scattering. I doubt we have any telescopes powerful enough to resolve far enough though, planets are pretty tiny.
Yeah I have some passing familiarity with this from reading a few papers about the Venus phosphine thing from about a year ago that turned out to be a measurement error. If we can mess up measuring the closest planet, think about how hard it is to see planets light years away.
Some molecules are unstable and unlikely to be in high concentrations but also leave obvious spectra (like O2, O3, CH4). You can tell by atmospheric scattering. I doubt we have any telescopes powerful enough to resolve far enough though, planets are pretty tiny.
Yeah I have some passing familiarity with this from reading a few papers about the Venus phosphine thing from about a year ago that turned out to be a measurement error. If we can mess up measuring the closest planet, think about how hard it is to see planets light years away.