How Many Months Have 28 Days?

“How many months have 28 days?” is a fun riddle to get you into brainstorming. Without pondering upon it much, you might say, “Only one month, that is, February has 28 days”. However, the correct answer is twelve. Every month has 28 days. Even though it is right that February has exactly 28 or 29 days, this question is usually asked as a tricky riddle. All the months in both the Julian as well as Gregorian calendars consist of 28 or more days. In the Gregorian calendar, seven months have a length of 31 days and four months, 30 days long.

The only month which is 28 days long during the common years, in February. The month has 29 days in leap years.  January, March, May, July, August, October and December have 31 days each, while April, June, September, and November have 30 days each.

A month, used with calendars, is a unit of time that is almost as long as the natural period in relation to the Moon’s motion. The moon and month are cognates. It was the cycle of the phases of Moon that the traditional concept of months arose. Such lunations (months) last for around 29.53 days and are known as synodic months. Researchers have excavated tally sticks that deduce that humans used the Moon phases to count days as early as Paleolithic Age. These synodic months are based on the orbital period of the Moon with respect to Earth-Sun life. These are used for dividing years even today and form the basis of numerous calendars.

Synodic months are the most familiar lunar cycle. They can be called the time intervals between two occurrences of a specific phase (such as the full moon or new moon) when seen by the observer on land. If we look at its mean length, a synodic month lasts for 29 days, 12 hours, 44 minutes, 2.8 seconds or 29. 53059 days. As the lunar orbit across Earth is eccentric ( and to a lower extent, the elliptical orbit of Earth around the Sun), the synodic month can have lengths varying for as many as seven hours. (See What Is The Average Amount Of Workdays In A Month?)

The months that we commonly know get their names from the ancient Romans. It was in the seventh century B.C. when Numa Pompilius established the first calendar. It was a revised version of an ancient Roman calendar with ten months. Januarius and Februarius were the two months added by Pompilius. Later in 46 B.C., the calendar was changed yet again by Julius Caesar, and the one with 365 and ¼ days was adopted. It remained in circulation until 1582. Then, Pope Gregory XIII got eleven days removed from the calendar. It was after this time that a new system with leap years was brought into effect.

This calendar came to be known as the Gregorian Calendar, named after Pope Gregory XIII. Initially adopted in 1582 by numerous Roman Catholic within Europe, it received its share of scepticism from Protestants. Most of the Protestant countries were against it, and some of them even believed Antichrist was behind the invention of this calendar. However, it gradually spread to the rest of the world thereafter. Greece was the last country which adopted this diabolical calendar in the year 1923.