The Bully Mnemonic & Calendar Variations

---

Bully Mnemonic Topics:

• The Bully Mnemonic
• The Bully Mnemonic & Calendar Variations

---

The Bully Mnemonic reminds us that there are approximately 31556928 seconds in a tropical year:

$$1TropicalYear\approx (10330-0.40)\times 3055sec=31556928sec$$

Knowing the number of seconds in a tropical year can help one understand the structure of various calendars, which typically are attempting to approximate the tropical year as a multi-year average.

Julian Calendar & Gregorian Calendar

There are 86400 seconds in a day:

$$1Day=24hours\times \frac{60min}{1hour}\times \frac{60sec}{1min}=86400sec$$

The number of seconds in 365 days is:

$$365Days=365\times 86400seconds=31536000seconds$$

The number of seconds in 366 days is:

$$366Days=366\times 86400seconds=31622400seconds$$

which is 24.222% of a day less than a full tropical year:

$$\frac{1TropicalYear-365Days}{1Day}=\frac{31556928sec-31536000sec}{86400sec}$$

$$\frac{1TropicalYear-365Days}{1Day}=\frac{20900sec}{86400sec}=24.222...\mathrm{\%}$$