Showing news stories on a timeline has been tried before. But Time Explorer, a prototype news search engine created in Yahoo's Barcelona research lab, generates timelines that stretch into the future as well as the past.

Time Explorer's results page is dominated by an interactive timeline illustrating how the volume of articles for a particular search term has changed over time. The most relevant articles appear on the timeline, showing when they were published. If the user moves the timeline into the future, articles appear positioned at any point in time the text might have referred to.

This provides a new way to discover articles, and also a way to check up on past predictions. The timeline for 2010 becomes a way to discover a 2004 Op-Ed suggesting that by now, North Korea would have constructed some 200 nuclear warheads, or a 2007 article accurately predicting difficult policy decisions for Democrats over the expiration of George Bush's tax cuts.

News organizations are increasingly turning to new ways of presenting their content, including through enhanced forms of search. A Pew research study in 2008 found that 83 percent of people looking for news online use a search engine to find it.

Time Explorer can spot both absolute references to future times, such as "November 2010," and work forward from an article's publication date to figure out relative timings like "an election next month." It also extracts names, locations, and organizations mentioned in articles. These are shown in a box to the right of the results; they can be used to add a person or other entity to the timeline, and to fine-tune results to home in on combinations of particular people or places.

"You can see for wars or any other event not only the people that are important, but when they became important," says Michael Matthews, a member of the Yahoo research team. "The evolution of news over time is not something you can do very easily with tools that are out there today."

Time Explorer was built using a collection of 1.8 million articles released by the New York Times stretching from 1987 to 2007 to stimulate research into new ways of exploring news coverage. Time Explorer was presented, along with other ideas for using the same dataset, at a session of the Human Computer Interaction and Information Retrieval (HCIR) workshop in New Brunswick, NJ, over the weekend. Time Explorer won the most votes from attendees for best use of the Times articles.

Other tools presented at HCIR attempted to assess the authority of people mentioned in an article, determine phrases related to a search term, and rapidly pull together a page summarizing the latest news on a particular topic, for example a celebrity or country.