A very important aspect of astronomy often overlooked is how much our eyes don't tell us. We see a very limited range of the spectrum of light emitted by astronomical objects, and many times it's what we don't see that tells us what's going on. That's why the European Southern Observatory has the HAWK-I camera: it sees in the infrared, in wavelengths invisible to our eyes. And when we train it on the skies, well, we see some pretty cool stuff. Like, say, gorgeous spiral galaxies: