1. A method of explaining bursty events, the method comprising: receiving an event stream, wherein the event stream comprises a plurality of search queries submitted to a search engine; identifying a bursty event cluster, within the event stream, that comprises search queries within a time period relating to a common subject, the identifying comprises the steps of: merging, into the bursty event cluster, search queries of the event stream that share a threshold fraction of search engine results returned by the search engine in response to the search queries; and merging, into the bursty event cluster, search queries of the event stream that share a threshold fraction of query terms; and determining a genre associated with the common subject; analyzing a source of data separate from the event stream that corresponds to the determined genre, relevant to the common subject of the bursty event cluster, wherein the analyzing comprises the steps of: receiving a relevant data stream separate from the event stream, the relevant data stream comprising events from at least one source of data corresponding to the time period; and identifying an explanatory event from the relevant data stream, wherein the explanatory event aids in interpreting the occurrence of the search queries of the bursty event cluster.