Well this isn’t exactly a surprise, considering how many people on Twitter tweet whatever is on their minds at any given moment: a new study conducted by Cornell University researchers and published in the journal Science found that the social media outlet documents our emotional states. Poring over more than 500 million tweets sent in 84 countries during two years for signs of good and bad moods, two researchers found a pattern: we start the day on a high note and leave work feeling a little more glum, but then our moods brighten when we go home to family, friends, and entertainment. But a more important finding lies behind these somewhat obvious truths. “This is a stone in the foundation of a new social science that is being built,” remarked a sociologist at Harvard University who was not involved in the study. “We’re in a similar place that we were in the 17th century with the discovery of the telescope and microscope.” Studying tweets is a way of tracking the moods of individuals and even populations, but it also provides researchers a way to home in on other worldly questions, like how and at what rate news events, politics, and the economy affects people’s emotional states. Ultimately, the study’s findings suggest that Twitter and other forms of “massive passive” data may lead to high-tech tracking of social and emotional trends, the way that analysts predict stock market trends.