how do we know what stuff in space is made out off?

you know how they say that "the space cloud is made of alcohol" or something like that, how is that determinable

?2015-08-17T21:09:33Z

Favorite Answer

They use a Spectrometer.

https://en.wikipedia.org/wiki/Spectrometer

quantumclaustrophobe2015-08-18T09:54:34Z

We analyze the light we see it with. If the chemicals and atoms in a nebular are excited by a nearby star - meaning, if the light of that star forces electrons into higher orbits - then, when the electrons fall to their nominal states, they emit photons in certain wavelengths... Hydrogen emits light in two wavelengths, water in 3, oxygen in a single one that I know of, and alcohol has a few also. We analyze the light we see - and can determine what chemicals are present by the "fingerprint" in the spectrum... Starlight shining *through* a cloud will have some of it's light absorbed, leaving black gaps in the rainbow spectrum we expect (and absorption spectrum), and other times there's small bands of light in different colors against a black background - this is an emission spectrum.

Larry Phischman2015-08-17T21:38:11Z

Spectral analysis. We analyze the light bouncing off it, and compare it's signature to known chemicals.

Tom S2015-08-18T11:56:51Z

Spectroscopy mostly.

Anonymous2015-08-17T21:06:13Z

Space probes