A picture of a dress set the Internet ablaze last week. The photo’s ambiguous light source creates a powerful visual illusion: to some viewers, the dress looks black and blue; to others it’s plainly white and gold. Social media users around the world latched on, and the science behind the illusion became a major part of the conversation. You can’t buy this kind of popular attention to a scientific question. But you can learn from it. How can science communicators get better at igniting this type of widespread, passionate, educational, and fun conversation online? What are some of the key lessons we can draw from the phenomenon of the black and blue dress (I swear, it is black and blue).