1. A method implemented by one or more computing devices, the method comprising: identifying, by a processor of one of the one or more computing devices, a temporally-ordered sequence of documents based on a search query received from a client device; identifying, by a processor of one of the one or more computing devices, in a particular document of the temporally-ordered sequence of documents, novel content including content not present in other documents of the temporally-ordered sequence of documents; assigning, by a processor of one of the one or more computing devices, a score to the particular document based on an amount of the novel content in the particular document; and ranking, by a processor of one of the one or more computing devices, the particular document among the temporally-ordered sequence of documents based on the assigned score.