Just like Neil deGrasse Tyson will be forever known as Pluto’s discombobulator – for everyone who still thinks Pluto is a planet, even though it was the International Astronomical Union who was responsible for demoting Pluto – via VOTING, Sosigenes of Alexandria might be accountable for leaplings despite what we think of Julius Caesar.
Leaplings, according to the dictionary, are people who have their birthday once every four years on the 29th of February. And all of that because of one man.
So what did Sosigenes do?
According to Pliny (Roman author, naturalist, natural philosopher, naval and army commander and now a beer),
… There were three main schools, the Chaldaean, the Egyptian, and the Greek; and to these a fourth was added in our country by Caesar during his dictatorship, who with the assistance of the learned astronomer Sosigenes brought the separate years back into conformity with the course of the sun.
Pliny, Natural History 18.211
A mathematician of the famous Alexandrian School, Sosigenes, knew his maths. He figured out Mercury’s orbit, in a long line of scientists who studied it, finishing with Albert Einstein. Sosigenes confirmed Babylonian astronomer Kidinnu’s observations: Mercury is never further than 22° from the Sun. How much work he did for Caesar, however, it is unclear. That’s because Caesar really liked astronomy (Dialetis, D. (2007). Sosigenes of Alexandria. In: Hockey, T., et al. The Biographical Encyclopedia of Astronomers. Springer, New York, NY.)! He liked astronomy so much that even wrote a treatise. “De Astris” (About Stars), was like a really good farmer’s almanac, a hit with the astronomy fans of the season.
The Genesis of Leap Years
The story of leap years begins in 45 BCE. The with the Roman calendar was in disarray, having drifted significantly from the seasonal cycle it was meant to track. It wasn’t tracking, actually. The amount of time it takes the Earth to go around the Sun is 365.2422 days. The amount of time it takes to have a lunar year is 12 lunar months, about 354 days. How did the Romans cope?
Before Julius Caesar’s reform, the Roman calendar had months that varied in length. The year was typically 355 days. February was chopped and changed a couple times. Here and there they would sneak in an intercalary month, called Mercedonius or Intercalaris, to align with the solar year.
Solar vs Lunar years
Many cultures had to deal with this. In the 3rd century BCE by Ptolemy III Euergetes suggested a similar arrangement as Sosigenes and Caesar later implemented. His subjects had refused to follow it. Some cultures who would have had enough of the Moon nonsense switched to a solar year. They were in dire need to measure the middle of winter accurately so they could plan their food supplies and not starve. The winter solstice is a popular date among those who experience a snowy season.
Out of sync
The amount of time takes Earth to go around the Sun once does not match 365 full days. Nor 366. It’s like the Earth needs 365 days and a morning. Or a good afternoon. Preciselly 365.2422 – that is 365 days, 5 hours, 48 minutes, and 46 seconds. This is the length of a tropical year (or a solar year).
90 days were added to the calendar to bring the year back in sync.
So the legend goes that Sosigenes proposed a simple yet revolutionary solution. Add a day to the calendar every four years. It accounts for the extra approximately six hours it takes the Earth to orbit the Sun beyond the 365-day year. This leap day, added to February, brought the calendar back in alignment with the Earth’s annual journey around the Sun.
Leaplings: Born into Rarity
Leaplings, those born on the elusive the 29th of February, owe their unique birthday to this ancient adjustment. With the day occurring only once every four years, leaplings find themselves in a rarefied group. The odds of being born on the 29th of February are about 1 in 1,461. Leaplings are a distinct minority in the global population.
Famous leaplings:
Jack Lousma – NASA astronaut (https://en.wikipedia.org/wiki/Jack_R._Lousma), Tony Robbins (motivational speaker) and Gioachino Antonio Rossini (composer) and the most famous of all, Superman – all are celebrated on the 29th of February.
Jack Lousma was the Pilot on Skylab 3, the second crew aboard America’s first space station – July 28 to September 25, 1973. This was NASA’s longest manned mission at the time.
Tony Robbins is famous for being a motivational speaker, Gioachino Rossini composed the William Tell overture,