The fact that the Earth takes 365 days to go around the sun, What for us is a year, is something that everyone knows. But It is an inaccurate data. One complete revolution of our planet around the Sun takes exactly 365 days, 5 hours, 48 minutes and 45.25 seconds. It seems that this «extra» time is not very relevant, but no matter how small it is, it is a fraction that must be taken into account since it is necessary to maintain the synchronization with our orbit.
This confusion worried scholars since the beginning of time, since these «extra» hours caused a problem: the calendar year did not coincide with the year marked on the calendar and there was an imbalance with the passing of the seasons. Something had to be done so that our calendar will adapt to nature’s calendar. After all, our lives are organized around a calendar and living in tune with the rhythms and cycles of nature is not only important to organize ourselves as a society, but it is one of the keys to physical and mental well-being.
After many attempts to resolve this mismatch, already in Egyptian times, it was decided that a day had to be added for the calculations to balance.
The Romans created the leap year
The ancient civilizations They were basically guided by the stars and celestial movements and it was necessary that the astronomical and chronological dates coincide so that, for example, solstices that mark the change of season occur on approximately the same dates year after year. The Sun and the path of the Earth around it could not be ignored: lunar cycles have always marked harvests and important events, even religious calendars determine the dates of some of their traditions by the lunar calendar.
It was calculated, then, that the «leftover» time of the Earth’s journey was almost a quarter of a day per year, so the Romans added a whole day every 4 years. They were the ones who placed it after the sixth day of the third week of the month. Hence the word ‘leap’, which comes from Latin ‘bisextus’, that is, «twice sixth».
But the mathematical calculations brought to light a problem: the real advance is not a quarter of a day (0.25) but is something less (0.242). So with each passing year, the Julian calendar was 0.008 days ahead of nature.
Centuries passed where these tenths accumulated and in the 16th century there were already 10 days ahead. So Pope Gregory XIII took matters into his own hands and eliminated certain leap years. It was determined that the additional day would be added only to the years at the beginning of the century divisible by 40 and that the leap years were divisible by 4.
After this, most of the world has adopted the Gregorian calendar and its leap year system, so that the days and months coincide with the key dates of the solstices.
What happens to the Moon in leap years?
It may happen that the month of februarywhich only has 28 or 29 days in leap years don’t have a full moon.
The period from one full moon to anotherpassing through all the lunar phases, It is about 29.5 days. so since February is shorter it may not have a full moon. This is not the case of this year 2024 but this phenomenon, the black moonoccurred in 2018 and will happen again in 2037.
By the duration of the lunar cycle what is impossible is that in February we can observe the blue moon, that is, a month with 2 full moonssince when it occurs in other months, we see the first one on the first or second day of the month, and in February there would not be time for the second one to occur.