### 5.5.4 Enable surprise

Now that you have heterogeneous people working together on a meaningful scientific problem, and you have their attention focused on where it can be most valuable, be sure to leave room for them to surprise you. It is pretty cool that citizen scientists have labeled galaxies at Galaxy Zoo and folded proteins at Foldit. But, of course, that is what these projects were designed to enable. What is even more amazing, in my opinion, is that these communities have produced scientific results that were unanticipated even by their creators. For example, the Galaxy Zoo community has discovered a new class of astronomical object that they called “Green Peas.”

Very early in the Galaxy Zoo project, a few people had noticed unusual green objects, but interest in them crystallized when Hanny van Arkel, a Dutch school teacher, started a thread in the Galaxy Zoo discussion forum with the catchy title: “Give Peas a Chance.” The thread, which began August 12, 2007, started with jokes: “Are you collecting them for dinner?,” “Peas stop,” and so on. But pretty soon, other Zooites started posting their own peas. Over time the posts became more technical and detailed, until posts like this started showing up: “The OIII line (the ‘pea’ line, at 5007 angstrom) that you are following shifts towards the red as $$z$$ increases and disappears into the infra-red at about $$z = 0.5$$, ie is invisible” (Nielsen 2012).

Over time, the Zooites were gradually understanding and systematizing their observations of the peas. Finally, on July 8, 2008—almost a full year later—Carolin Cardamone, an astronomy graduate student at Yale and member of the Galaxy Zoo team, joined the thread to help organize the “Pea Hunt.” More enthusiastic work ensued and by July 9, 2009 a paper had been published in the Monthly Notices of the Royal Astronomical Society with the title “Galaxy Zoo Green Peas: Discovery of a Class of Compact Extremely Star-Forming Galaxies” (Cardamone et al. 2009). But interest in the peas didn’t end there. Subsequently, they have been the subject of further research by astronomers around the world (Izotov, Guseva, and Thuan 2011; Chakraborti et al. 2012; Hawley 2012; Amorín et al. 2012). Then, in 2016, less than 10 years after the first post by a Zooite, a paper published in Nature proposed Green Peas as a possible explanation for an important and puzzling pattern in the ionization of the universe. None of this was ever imagined when Kevin Schawinski and Chris Lintott first discussed Galaxy Zoo in a pub in Oxford. Fortunately, Galaxy Zoo enabled these kinds of unexpected surprises by allowing participants to communicate with each other.