An ancient Mexican city that housed a temple used for astronomical observations. The temple was built more than 2,000 years ago, and some of its structures align with the point on the horizon where Capella made its first dawn appearance. That appearance happened on one of the two days of the year when the Sun passed directly overhead — dates that were vital to the city’s ritual life. So Capella might have acted like a warning flag, alerting the city’s leaders that the time for the year’s most important ceremonies was at hand.
