Murray Gibson (center), dean of the College of Science, says that without a leap day every fourth year, summer would drift out of sync about one month every 100 years or so. Photo by Mary Knox Merill.
Today is Feb. 29, the extra day we add to the calendar in leap years. But why do we need this extra day, and what is the science behind it? And what about the lesser-known leap second – which delegates from more than 70 nations recently debated whether to abolish? We asked Murray Gibson, dean of the College of Science, to answer these questions – as well as how early scientists discovered the need to adjust the calendar.