It’s a season of sometimes grim anniversaries (e.g. 150 years since the start of the American Civil War, 100 since the Triangle Shirtwaist Factory fire, one since the Gulf oil spill), and today marks 25 years since the beginning of the Chernobyl nuclear disaster.  The Big Picture hosts a haunting image collection, and the NYT’s Lens blog goes into more detail on the few who’ve stayed behind.