It was my original intention to thoroughly read up on Smart Dust in the past week to prepare for my research and to gain a solid mathematical footing for this post. However, due to several exams and assessments with which I have been occupied, the “time got away from me,” and I was only able to read broad introductory pieces into the history and basic terminology associated with the technology. Thus, it is only fitting to freshly resume my endeavor after Spring Break—and to go into the break discussing time, particularly the calendar anomalies associated with this time of year.

1. Leap Day

This past Saturday was February 29, a day supposedly annexed to the shortest month every four years to account for the inexactness of a 365-day year. I say supposedly because it is popularly believed that any year divisible by 4—alternatively, every presidential election year—is a leap year. However, the algorithm has one caveat that has not been of interest recently but may be of interest to us should we live long enough to experience it:

A. Any year divisible by 4 and not by 100 is a leap year

B. If a year is divisible by 100, it must also be divisible by 400 to be a leap year.

Image Courtesy of General Blue

The second provision dictates that while years such as 1600, 2000, and 2400 are leap years like any other, century years not divisible by 400 (e.g., 1800, 1900, 2100, 2200) are not leap years. This was precisely the adjustment made by Pope Gregory XIII in 1582, when the dates of October 5-14 were eliminated to correct the fallacy of the Julian Calendar (the assumption that a leap year should unconditionally be every four years), which had let the calendar drift 12 days askew. To this day, the Gregorian Calendar forces leap-day babies who live through century years such as 1700, 1800, 1900, etc. to wait 8 years between birthdays instead of the already-intriguing 4. For the historian’s appeal, Thomas Jefferson and William McKinley are the only two U.S. presidents to have been elected in common years (non-leap years), and whoever is sworn in on January 20, 2101 will be the third.

2. Daylight Saving Time

This Sunday, March 8 (unless you are traveling to Hawaii or the non-Navajo part of Arizona for Spring Break), you will experience a 23-hour day, with 1:59 AM changing to 3:00 AM. The agricultural and statistical reasons for Daylight Saving Time (DST) notwithstanding, there is a growing movement to either abolish it (“fall back forever”) or stay in DST for 12 months of the year instead of the traditional 8. Keep in mind that the switch to and from Daylight Saving Time shifts the daily sunrise and sunset times by one hour; one can analyze this in the context of the longest and shortest days of the year (June 21 and December 21, respectively, with the opposite true in the Southern Hemisphere):

Currently, in State College (about 40 degrees N latitude), the Sun rises and sets at approximately 5:30 AM and 9:00 PM, respectively, on the summer solstice (6/21), which is in DST. Without DST, these times would be 4:30 AM and 8:00 PM.

On the winter solstice (12/21), which is in standard time, the Sun rises and sets at approximately 7:30 AM and 5:00 PM. If DST were year-round, these times would be 8:30 AM and 6:00 PM.

Image Courtesy of Business Insider

Image Courtesy of Blue Delaware

Based on this information, what is your opinion of Daylight Saving Time? Would you abolish it in favor of a super-early sunrise and a more modest sunset time in the summer, or would you abolish standard time to obtain an extra hour of daylight in evenings while waking up to darkness in the winter?

3. When Is Easter?

As a Catholic, Easter Sunday is the holiest day of the liturgical year. While it is not until April 12 this spring, the theme of this final pre-Smart Dust post bestows the ideal opportunity to discuss the little known formula of how the date is determined. In 2019, Easter fell on April 21; in 2018, April 1; in 2017, April 16. Next year, it will fall on April 4, 2021. The date seems to constitute a randomly chosen Sunday in March or April without rhyme or reason. However, it is actually derived as follows:

Easter falls on the first Sunday after the first full moon after the Vernal (Spring) Equinox.

For example, this year, the Vernal Equinox—“first day of spring”—is on Thursday, March 19. The next full moon after the equinox occurs on Tuesday, April 7. Easter is thus celebrated on the following Sunday, April 12. If the so-called paschal full moon happens to occur on a Sunday, Easter is placed the following week in lieu of the same day.

Due to the quasi-periodic nature of the moon phases, there exists an algorithm to mathematically determine the date of Easter Sunday for any given year. I will not regurgitate the algorithm in this post, but I link to it here and highly encourage you to read about it yourself. As an exercise, use the algorithm to determine Easter Sunday in your birth year (probably 2000 or 2001) and compare your result to a Google search.

Image Courtesy of Active Christianity