Leap year 2024: An extra day — Feb.

29 — for most of us, a once-in-four years’ birthday for a select few.

We can thank the ancient Egyptians for this essential astronomical invention, according to a fascinating document carved into a 3rd century B.C. stone tablet, the Canopus Decree of 238 B.C. It was “written in Egyptian hieroglyphs and Demotic script, with an ancient Greek translation beneath.” (Indi Bains, “This 2,200-yearold slab bears the world’s first mention of leap year,” National Geographic, Feb. 21, 2024) Bains explains that by 238 B.C., Egypt’s 365-day calendar had been in use since 2,600 B.C. It had 12 30-day months and “5 epagomenal days (‘monthless days) added to the calendar to make it approximately equal to the solar year.” Egyptians had long known and trusted that Sirius, the brightest star in the sky, would reappear just as the Nile flooded. The deposition of silt during that time ensured that Egypt’s farmland would remain fertile for the growing season.

Sirius was not visible to the ancient Egyptians for the same 70 contiguous days of every year because it was too close to the sun. Annually after this absence, Sirius would reappear on the eastern horizon in the dawn sky, rising close to and just before the sun — a phenomenon known as “heliacal rising.”

Sirius’s rising at the summer solstice, in tandem with the Nile’s beneficial flooding, was also the beginning of the Egyptian New Year.

“By measuring the elapsed time between each annual heliacal rising of Sirius, astronomers eventually realized the solar year was a quarter-day longer than 365 days.” Unfortunately, “Ptolemy III’s directive in the Canopus Decree to add an additional day to the calendar every four years was ultimately unsuccessful.”

Interestingly, Bains writes, “when the Romans annexed Egypt in 30 B.C., the Egyptians were again using a 365-day calendar, and by 22 B.C — a few years after the Egyptian-inspired Julian calendar had been implemented in Rome — Emperor Augustus (Julius Caesar) had reintroduced the leap day back to the Egyptians.” In 1570 Pope Gregory XIII commissioned the Jesuit astronomer Christopher Clavius to modify the Julian Calendar.

New Year’s Day was no longer observed since the calendar now had a 10-day error.

(“The reason for the latter was that Caesar and Sosigenes (Alexandrian philosopher) failed to calculate the correct value for the solar year as 365.242199 days, not 365.25 days.

Thus, an 11-minute-ayear error added seven days by the year 1000, and 10 days by the mid 15th century.” (Evan Andrews, “5 Ancient New Year’s Celebrations,” History.com, Dec. 4, 2023) The essential Christian date of Easter was also affected by the 10-day error, since Easter is supposed to be observed on the first Sunday following the first full moon after the vernal equinox.

We still follow the Julian calendar today; the fix for its 11-minute-a-year error was to eliminate 10 days in 1582 and the leap year day for the century years not divisible by 400. Afterward, the century years 1700, 1800, and 1,900 had no leap days, but the last one, 2000, divisible by four, did. So far, no other changes to the calendar have been needed.

After today’s extra winter day, meteorological spring arrives tomorrow. Our transitional spring season, however, feels like a continuation of winter in Ouray most years. The higher sun angle of late February and March does melt snow faster, though.

This year we’re already firmly ensconced in mud season. In a typical March we whipsaw between snow packed roads and messy mud puddles scattered between deep brown potholes. A clean car is a rarity which never lasts for more than a day or two.

March is, on average, the fourth snowiest month of the year as well as the fourth wettest. But the mean high temperature of 47.2 is 6.5 degrees higher than February’s 40.7. March nights average 24.6, a good 6.4 degrees warmer than February’s 18.2.

What might March bring this year?

Snow, mud and greening grass for the first weekend? We’ll see.

Unfortunately, this winter’s snowfall and precipitation remain well below average. As of Tuesday morning, February had only 15.8 inches (52%) of normal snowfall, 30.4 inches. Precipitation is 1.12 inches (64%) of the normal 1.74, Water Year October 2023-February 2024 shows a slightly better 6.69 inches (75%) of normal precipitation, 8.9 inches. Snow Year July 2023-February 2024 shows 85.6 inches (74%) of normal snow, 116.6 inches.

The National Oceanic and Atmospheric Administration currently predicts much cooler and wetter weather for this area over the first three weeks of March, beginning this weekend. That’s sorely needed after a droughty winter following a very dry summer and fall.

Let it snow — it will be summer soon enough!

For jaywalkers every year is leap year.

— Bill Holman, “Auto Suggestions,” The Travelers Insurance Company, Thou Shalt Not Kill! 1935 Karen Risch gardens, records weather for NOAA and CoCo-Rahs, writes and hikes in Ouray. Her Wunderground weather station ID is KCOOURAY3, transmitting weather from latitude N38 1’ 34”, longitude W107 40’21”, Elevation 7,736’. A purpleair. com air quality monitor RISCH operates at the same location.