There are many types of objects in space that just can’t be seen with visible light, and many more that have very different features when observed across the electromagnetic spectrum.  A prime example of the former is a molecular cloud.  Cold, incredibly huge, and full of low density Hydrogen, these clouds are the raw material for star forming galaxies.  If stars begin to form within them, they can be seen as gorgeous nebulae, but when alone in the darkness of space we need to look for the dim signature of radio waves they emit. The Smith cloud, named after it’s...