Golomb’s Gambits Calendar Oddities
December 8, 2010 |  by Solomon Golomb


Identify the common feature shared by the five members of each one of the following sets of holidays or commemorations (a different feature for each set).

1. New Year’s Day

Groundhog Day

Cinco de Mayo


Armistice Day

2. President’s Day

Mardi Gras


Labor Day


3. Valentine’s Day

St. Patrick’s Day

Flag Day

Bastille Day

Christmas Day


Arrange the following lunar “months” in order of length (from shortest to longest) and explain how each is determined.

1. anomalistic month

2. nodal month

3. sidereal month

4. synodic month

5. tropical month


Translate the following terms from their calendrical meanings into plain English.

1. dominical letter

2. ephemeris

3. intercalate (verb)

4. bissextile (adj.)

5. embolism (noun)



1. If septum is Latin for “seven,”

why is September the ninth


2. Why does the Muslim year

average only around 354 days?

3. If summer officially begins

with the summer solstice

(usually between June 19 and

June 23), why is Midsummer

Day celebrated on June 24?

4. Why did the Soviet Union

celebrate the “October

Revolution” in November?

5. What is the origin of

“thermidor” in lobster thermidor?