Play with the Milky Way

When you hear the words "Milky Way" in the context of astronomy, more than likely you envisage a galactic disk. But how do you know it's a disk? You certainly can't see any disk. If you go beyond the city limits to reduce the ambient light pollution, at best you will only see a dense band of stars, not a disk.

The notion of a galactic disk was inferred from this plot:


made painstakingly by the German-English musician and amateur astronomer, William Herschel in 1785. The modern rendition looks like this:


This one was also made by an amateur, an amateur photographer named Nick Risinger, and it's composed of 37,000 separate photographs. Not only that, but there's an interactive version. Wiredscience has the full story.