Tuesday the 13th

Tuesday the 13th is a date that occurs when the 13th of a month falls on a Tuesday. It is an unlucky day in Greece, Spain, and Latin America. Tuesday the 13ths occur at least once in each year but can occur up to three times in one year.

## Why is it Unlucky?
### 1. The Day "Tuesday" 
* In Spanish, Tuesday is called **"Martes,"** named after **Mars**, the Roman god of war. Mars symbolizes conflict, destruction, and violence, which gives the day a sense of foreboding.
* In Greek mythology, Tuesday is linked with Ares, the Greek equivalent of Mars, reinforcing associations with bad luck and chaos.

### 2. The Number 13 
* Just like in other cultures, the number 13 is considered unlucky. It is often seen as irregular or incomplete compared to 12, which is considered a "perfect" number (e.g., 12 months, 12 zodiac signs, 12 apostles).
* In Christian tradition, 13 is sometimes connected to the Last Supper, where Jesus dined with his 12 apostles before his betrayal and crucifixion.

### 3. Historical Events 
* **Fall of Constantinople (1453):** In Greek history, Tuesday is remembered as the day Constantinople fell to the Ottoman Empire, marking the end of the Byzantine Empire. This occurred on May 29, 1453, which was a Tuesday. The event was devastating for Greeks and is still considered an unlucky association with the day.

### 4. Cultural Traditions 
* In Spain, Greece, and Latin America, the combination of Tuesday and 13 intensifies bad omens because both the day and the number are seen as inauspicious on their own. Together, they are considered doubly unlucky.

## Occurrence
The 13th falls on a Tuesday in months that begin on a Thursday. There is at least one Tuesday the 13th in every calendar year but there can be up to three in one year.

### Frequency
The longest period that occurs without a Tuesday the 13th is 14 months, either from July in a Leap year starting on Thursday or Common year starting on Friday to September of the following year being a Common year starting on Saturday (e.g. 2004-2005, 2010-2011 and 2021-2022) or from August in a Common year starting on Tuesday to October the following year being a Leap year starting on Wednesday (e.g. 1991-1992 and 2019-2020). The shortest period between two Friday the 17ths is 1 month from February to March in a Common year starting on Monday (e.g. 2001, 2007, 2018 and 2029).

### Frequency within a single year
There can be no more than three Tuesday the 13ths in one year. This happens in the months of February, March and November in a Common year starting on Monday (e.g. 2001, 2007, 2018 and 2029) and January, April and July in a Leap year starting on Thursday (e.g. 1976, 2004 and 2032).
In the 1990s, there was one Tuesday the 13th in 1991, 1992, 1995 and 1997, two in 1993, 1994, 1996, 1998 and 1999 and three in 1990 for a total of 17 Tuesday the 13ths in the 1990s. In the 2000s, there was one Tuesday the 13th in 2000, 2002, 2003, 2006 and 2008, two in 2005 and 2009, and three in 2001, 2004 and 2007 for a total of 18 Tuesday the 13ths in the 2000s. In the 2010s, there was one Tuesday the 13th in 2013, 2014, 2017, and 2019, two in 2010, 2011, 2012, 2015 and 2016 and three in 2018 for a total of 17 Tuesday the 13ths in the 2010s. In the 2020s there was one Tuesday the 13th in 2020 and 2023 and two in 2021, 2022 and 2024. There will be one Tuesday the 13th in 2025 and 2028, two in 2026 and 2027 and three in 2029 for a total of 17 Tuesday the 13ths in the 2020s. This information shows that the frequency of Tuesday the 13ths increased in the 2000s and decreased a bit in the 2010s and 2020s.