Best of 2015: The Idiot's Guide to Pluto

What was the biggest news in astronomy this past year? The editorial board of Discover has helpfully provided an answer, one that I heartily endorse (and not only because I wrote the related story in the magazine): It was the exploration of Pluto by the New Horizons spacecraft. To appreciate just why that mission was, and still is, such a big deal, join me in a little act of mental time travel. If you could move 6 months back in time, it would be shockingly simple to summarize what astron