Dr Minjae Kim, Research Fellow, Department of Physics, University of Warwick, said:

"Leap years play a crucial role in aligning our calendar with the Earth's orbit around the Sun. The orbit, or tropical year, takes about 365.24 days to complete, slightly longer than our standard calendar year of 365 days. This extra quarter of a day each year may seem insignificant, but over time, it adds up, leading to a noticeable shift in our calendar. Without adjusting for this extra time, our calendar would gradually fall out of sync with the astronomical seasons, causing a significant drift over the years. Leap years, therefore, are essential to prevent this drift and maintain the alignment of our calendar with the Earth's journey around the Sun.

"To counter this misalignment, the leap year system adds an extra day to the calendar every four years. This adjustment is made by extending February to 29 days. This seemingly simple solution of adding a day every four years is refined further in the Gregorian calendar, the most widely used calendar system today. It beautifully illustrates how we have harmonized our constructed concept of time with the natural rhythm of the Universe, maintaining a critical balance between human activities and the Earth's natural cycles."