2020, a leap year

 Comment 15: 2020, a leap year

A common year is 365 days long, but there are some years that have 366 days. They´re called leap years, and they add one day to February. This kind of years happens each 4 years, and that´s because the Earth takes 365 days and 6 hours, so every 4 years you´ve got 24 extra hours, which is a day.
This was intoduced in the 1 b.C, when Cesar changed the Roman calendar searching for a solution to the inequality of the seasons.
There are many people that have been born on that day, but of course they don´t only add years that day, so they celebrate their birthday the day before or the day after.
As a curious fact, in some countries it is thought that these days bring bad luck, so they say "año bisiesto, año siniestro". In Greece, they think that the whole year will bring bad luck, not only the day.