Tag Archives: year

Why Are There 360 Degrees in a Circle?

19 Monday Mar 2018

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Everyone knows there are 360 degrees in a circle. Why? A circle could have a 1,000° which would make a half circle equal 500° and a quarter circle 250°. Who chose the number 360? Was there a vote? Who do we blame? Inquiring minds want to know!

Two circles getting in each other's way

2017 Total Solar Eclipse from Canyon City, OR

As it turns out there are at least two reasons we use 360° as the number to define a complete circle. One reason has to do with astronomy and the other with mathematics.

360 Degrees? Blame the Babylonians

The Greeks are partly responsible for defining the numerical value for a circle, but really it was the Babylonians. It may even be farther back than the Babylonians, but someone erased their hard drive and now we will never know.

Apparently, the Babylonians loved the number ’60.’ They created a number system using Base 60 (we use Base 10.) The number 60 is amazing because it can be divided into so many factors. 60 can be divided evenly by 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, and 60. Since the Babylonians loved 60, the fact that a circle can be divided into six equilateral triangles made 360 the best option for defining the numerical value of a circle.

We don’t actually know if it was the Babylonians, but we do know that several prominent Greek mathematicians used 360° as the numerical value for a circle. It is written…in Greek of course.

Star Gazers In a 360 Days

But long before the Babylonians, it was obvious to anyone who looked up at the sky at night that the stars followed a circular pattern through the year. If one noted the position of a star or constellation on a particular night and time, next year that star would be in the same place on the same day and time.

The elapsed number of nights for a full circle? About 360. Anyone who tracked the stars would have noted that the circular pattern of the stars resumed after about 360 days.

The reason we have 360° is most likely because of the speed at which the Earth rotates, (once every 24 hours,) and there are approximately 360 rotations (days) in a year.

Metric Circles?

Believe it or not, there were attempts to make circles metric. It didn’t take. There are some uses for it, but the 360° value is more accepted ‘around’ (that’s a joke) the world.

The Ides of March is Really About the Moon

15 Thursday Mar 2018

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Thanks to William Shakespeare, the Ides of March is associated with the assassination of Julius Caesar (15 March 44 B.C.) Most people know the Ides of March to be on the 15th. The Ides of a month is often referred to as the middle of the month, which is true, but there is more. The Ides of March is about the Moon, not Caesar.

The Greek and early Roman calendar:  New Moon began each month (kalends) and the Full Moon was the middle (ides)

The Growing Pains of the Months and Years Concept

The concept of a month and a year was in a transitional phase during the rule of the Romans. Early calendars simply followed the phases of the Moon. A New Moon started each month and the Full Moon was the middle. This meant that the cycle of the seasons and the months were not in synch.

Each month included three reference points associated with the phases of the Moon. They were the  kalends (New Moon), nones (first half Moon,) and ides (Full Moon.) Every other day of the month was a number based on how long before the next named phase of the Moon (March 12 would be ‘3 days before ides.’)

However, there were only ten months in a year so they added Winter as an unnamed time period between the years to match the Spring, Summer, and Autumn. The New Moon prior to the Vernal Equinox would begin the new year. March was the first month of a new year and celebrations were held between the kalends and ides of March. For example, in 2018 the New Year (kalends of March) would be 17 March so the ides of March would be 31 March.

Back to J.C. …Julius Caesar

Cavete Idibus Martiis

Beware the Ides of March (in Latin)

The situation of Caesar’s death is interesting considering the current political environment of the United States. Caesar had won the support of the lower Roman classes and was named dictator for life. His assassination threatened the rise of a civil war led by the lower class. Antony used this threat in an attempt to take Julius Caesar’s place, but Caesar had named his 18-year-old son, Octavius, as his successor. In the end, the conspirators in the Senate were all killed and Octavius ruled Rome.