Previously, those who advocated for the 13-month calendar stated that it was a more stable way of divvying up the year. However, others stated that it wasn't as easily divisible as a 12-month variant.

"When Numa Pompilius took reign [of Rome], he decided to make the calendar more accurate by lining it up with the year’s 12 lunar cycles," according to the Children's Museum of Indianapolis. The ...

Here's what to know about the sacred Islamic month as it begins. When Does Ramadan Start and End? Ramadan is the ninth month of the 12-month Islamic lunar calendar.