eli5: Why does July & August have 31 days but February has only 28 ?

Question

eli5: Why does July & August have 31 days but February has only 28 ?

In: 123

Answer 1

Calendars were created to know when day and night are equally long and also to know when the longest and shortest days were. These four days stand out and are important for agriculture and culture.

Now, spring and summer are the longest in northern hemisphere with 93 and 94 days. Fall is 91 days and winter is 89 days. With all other months being 30 or 31 long, February just needs to be shorter. Esp. If you want to stick the four stand out days to the same date (in the long run).