22. The system of claim 21 , the computer program modules further comprising: a comparative feature extraction engine configured to extract event features from annotations associated with the event and to extract social media features from the plurality of social media content items; and the media/event alignment engine further configured to map the event to the social media content items based on a relationship between the event features and social media features.
21. A system for associating social media content items with a time-based media event, the system comprising: a computer processor; and a computer-readable storage medium storing computer program modules configured to execute on the computer processor, the computer program modules comprising: a data ingestion engine configured to access from a social networking system a plurality of candidate social media content items authored by users of the social networking system; a media/event alignment engine configured to determine a confidence score for each of the candidate social media content items indicative of a probability that the candidate social media content item is relevant to the event and to align with the event, based on their respective confidence scores, a subset of the plurality of the social media content items; and a data store for collecting the alignments between the event and the subset of the plurality of the social media content items.