[Wildbill22]

So I have to ask: how do you detect Iso-propyl cyanide from 27,000 light years away?

[SargeK]

Just guessing - absorption spectra?

[Natufian]

Read the article. That’s why it’s there.

[Professional Engineer]

Litmus paper.../s

I believe Sarge is correct.

[SargeK]

I stand corrected. Emissions spectra.

[Billthedrill]

As stars are born in the cloud they heat up microscopic dust grains. Chemical reactions on the surface of the dust allow complex molecules like i-propyl cyanide to form.

The molecules emit radiation that was detected as radio waves by twenty 12m telescopes at the Atacama Large Millimeter Array (Alma) in Chile.

Or so they say. Personally I think it was a really, really long cotton swab.

[InterceptPoint]

So I have to ask: how do you detect Iso-propyl cyanide from 27,000 light years away?

I can answer that:

You take a small sample and add some other chemical whose name I forget. If it turns purple then it's Iso-propyl cyanide. Simple. Although, it could be that it turns pink. Or blue. Or something like that. Don't ask how you get that sample. We didn't cover that in chemistry. And, lets face it. 27,000 light years is a long ways away.