Why leap years exist | Popular Science
Here’s a mind-bending thought: Time, if not measured, does not exist. People create calendars, with designated weeks and months, that sync to a variety of earthly and extraterrestrial cycles. The people of the Trobriand Islands in New Guinea, for example, used to start their year when a species of sea worms made their annual swarm onto their southern coasts. In our culture, we pick dates according to the way the sun and moon are moving. We have prioritized a calendar that matches with the solar year. Our months are made of lunar cycles, and we restart the year after the Earth has made one full rotation around the sun. But sometimes these cycles don’t sync up. If the sea worms didn’t show up at the usual lunar cycle period, the Trobrianers would say that the “moon has gone silly,” according to Kevin Birth, a professor of anthropology at Queens College and the Graduate Center at the City University of New York (CUNY). The year would thus be extended. Calendar followers have a similar, though more …