Cosmic Collections: creating a big bang

'Cosmic collections' was a Web site mashup competition held by the Science Museum in late 2009 to encourage members of the public to create new interfaces with newly accessible collections data prepared for the Cosmos & Culture exhibition. The paper reports on the lessons learned during the process of developing and running the competition, including the organisational challenges and technical context. It discusses how to create room for experimentation within institutional boundaries, the tools available to organise and publicise such an event on a limited budget, the process of designing a competition, and the impact of the competition. It also investigates the demand for museum APIs.