The Milky Way galaxy: The microwave version
This lovely image is of our home, the Milky Way galaxy, but in a way our mortal eyes cannot perceive it. It doesn’t show stars, but the stuff that makes (or will make) up stars and planets and whatnot — clouds of gas and dust.
Our eyes can see only a tiny fraction of light — the visible spectrum, ROYGBIV (rainbow colors) — but the universe also glows in other kinds of light: gamma ray, X-ray, ultraviolet, infra-red, microwave and radio. And each frequency tells us something different.
The atmosphere blocks some of those frequencies (fortunately for life in Earth), so to view the universe in this exotic light astronomers have to depend on telescopes out in space. The European Space Agency, for example, launched the Planck Surveyor telescope to capture images in the microwave range, like this one here.
Microwave imaging gives us two important sets of information about the Milky Way and the universe we are in.
First, the huge clouds of gas and dust in the galaxy (which are mostly invisible to our eyes) are what eventually turn into stars and planets (and all the stuff that ends up on planets). In the photo, those clouds are all those wispy bluish-white and pinkish-white tendrils stretching out from the center (the galactic equator).
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