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There's water vapor in the Milky Way, although the total amount is 4,000 times less than in the quasar, because most of the Milky Way’s water is frozen in ice.
by walkon 15y ago
There's water vapor in the Milky Way, although the total amount is 4,000 times less than in the quasar, because most of the Milky Way’s water is frozen in ice.
How could they possibly know this?
- sambeau 15y agoI am not an astronomer but I would guess they know this the same way they know what anything in distant space (that does not give off light of its own) is made-up of: they observe the light shining through it and see which part of the spectrum is/is not filtered by it.
- Rene_Descartes 15y agoThey can't, silly. They can just think that they observe it.
- sbierwagen 15y agoIt's phrased oddly, and I haven't read the original paper; but I assume they just measured the spectra of its infrared blackbody radiation. http://en.wikipedia.org/wiki/Black_body http://en.wikipedia.org/wiki/Black_body Just like how a noncontact infrared thermometer works, except you have to use a space-based telescope, due to the water in our atmosphere.