Critics have derided the 140-character messages posted daily on Twitter as trivialities. Yet to researchers, the popular social media site presents a rich trove of data. Barbara Poblete and her colleagues at Yahoo Research in Santiago analyzed tweets in the wake of February’s Chilean earthquake to learn how rumors propagate online. They found that people used Twitter to sort truth from falsehoods. Poblete’s group saw that 62 percent of tweets with earthquake-linked keywords from users in the Santiago time zone questioned or denied rumors that later turned out to be false. By comparison, when it came to confirmed truths, just 2 percent of tweets questioned them, and 0.3 percent were denials. Other researchers have used Twitter to track mood changes across the U.S. Alan Mislove, a computer scientist at Northeastern University, and Sune Lehmann, a Harvard University physicist, analyzed tweets that used words psychologists rated for emotional heft, such as “triumphant” and “suicide.” Their preliminary findings revealed that early mornings, late evenings and weekends rated the highest for happiness and that, unsurprisingly, the West Coast was happier than the East Coast.

The group now hopes to use Twitter to track changes in political climate. “Twitter is designed to be open, so we can look at content without violating anyone’s privacy,” Lehmann says. In April, Twitter announced it would donate its public tweet history to the Library of Congress. Researchers, at least, will be in a good mood about that.