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In this section of a wiki article it talks about scientist finding amino acids in outer space, or at least complex molecules and such.

Also this video says how there is alcohol in Sagitarius B2.

How are these detected?

Since I know we haven't sent any probles there, the only logical answer is spectroscopy.

So what's happening is they are looking through a telescope, have the computer do some analysis, then they see this

spectro 1

or this

spectro 2

and they say "hey, it's an amino acid, for sure!!"

Is that really all it takes and are these results that came from millions of kilometers away really accurate, unique, free of distortions, and reliable enough to say "it's an amino acid, for sure!"?

I'd have to imagine there might be interference and inaccuracies. I mean detecting the structure of something so tiny as a molecule from such large distances...? What's the magic they use or is it really just an educated guess and we're only like 53.7% sure that's what it is?

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    $\begingroup$ They don't say, "it's an amino acid, for sure!" They say that amino acids are the best explanation for the spectral lines and quantify what "best" means. $\endgroup$ – David Richerby Jun 14 '15 at 12:51
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The Wikipedia article you link to links to the Spectral signature page.

It says

Spectral signatures are the specific combination of emitted, reflected or absorbed electromagnetic radiation (EM) at varying wavelengths which can uniquely identify an object.

As with any science, I'd expect that such reports are at least at the 95% confidence level, or at the 99% level.

For conclusions regarding interstellar molecules, the observers need to spectroscopically identify the radiation the samples receive, then determine what molecules produce the signature that is detected.

As already mentioned in the quote, some of the radiation could be absorbed (filtered out), some could be reflected (toward us), and after absorption some could be radiated.

To reach a high confidence level, a sample of the gas (in the lab) would have to be irradiated with the detected stellar radiation spectrum and the resultant spectrum compared to the spectrum measured via the telescope.

The lab-derived result would have to be adjusted in the red or blue directions account for possible velocities in the remote gas cloud.

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