March 20th 2015 has the distinction of being a double Freaky Friday. I’m not talking about the 1976 movie where teen Jodie Foster and her mother Barbara Harris exchange bodies or the 2003 remake with Lindsay Lohan and Jamie Lee Curtis. FWIW I enjoyed the former and have never seen the latter, but I digress. I’m talking about a rare occurrence of astronomical and financial events that even the Mayans failed to predict. In fairness to them their calendar didn’t make it beyond 2012, so I’ll give them a pass.
Okay, what am I talking about? Financially, every third Friday of the last month in each calendar quarter is known as a Triple Witching day or sometimes called Freaky Friday. On that day stock index futures, stock index options, and stock options all expire. The combination generally leads to higher trading volume and occasionally more volatility. While this may cause some consternation for traders, bankers, and financial planners, it happens every three months and really isn’t that rare.
Astronomically three things are happening on the 20th. First, it’s an Equinox (Vernal in the northern hemisphere and Autumnal in the southern). Big deal, the Equinox happens twice a year. Fair enough, but it’s also a lunar perigee-syzygya event, more commonly called a supermoon. That’s when a new or full moon occurs when the moon’s elliptical orbit is at its closest point to the earth. Full supermoons appear brighter (~30%) and larger (~14%) than normal full moons. This event occurs during a new moon and would normally be invisible because the lighted side of the moon isn’t facing the earth. However, we can see the new moon – or at least its silhouette during a total solar eclipse. As you’ve no doubt surmised, that’s the final piece of this astronomical Freaky Friday. The full event will only be visible in extreme northern latitudes, but the Slooh Community Observatory will host a live broadcast. If you miss it, you’ll have three more opportunities this century, 2034, 2053, and 2072. Assuming Wall Street continues to do business as now, none of these Equinox eclipses will coincide with a Triple Witching day.
As a reward for those of you with the persistence, patience, and perseverance, to stick with this post here are my top 10 interesting (at least to me) facts and one bonus myth about the Equinoxes, calendars & eclipses:
- Equinox comes is Latin for ‘equal night’ implying 12 hours of day and 12 hours of night, but this is inaccurate for every location except those on the equator.
- Equinoxes is defined as when the center of the sun crosses the equator. Since the sun is bigger than a point of light and the Earth’s atmosphere refracts its light we actually get more than twelve hours of light on the Equinox.
- The Equinox is the only time that the sun rises directly in the east and sets directly in the west. The Great Sphinx points directly toward the rising sun on the day of the vernal equinox.
- Easter always falls on the first Sunday after the first full moon after the Vernal Equinox. Under the old Julian calendar with a year that’s 11 minutes too long the Vernal Equinox migrated a day earlier every ~128 years, which slowly moved Easter toward winter. By eliminating 3 leap years in every 100 the Gregorian calendar reduced the error to ~27 seconds. The Equinox now moves ~1 day every 3,200 years.
- The adoption of the Gregorian calendar varied from country to country, Catholic powers Italy, Spain & France adopted it in 1582, non-Catholic nations waited longer (UK 1752, Russia 1918, and Greece 1922).
- Moving to the Gregorian calendar required the ‘skipping’ eleven or more days. In 1752 the UK switched resulting in the loss of twelve days. One day it was Wednesday 2 September 1752 and the next it was Thursday 14 September 1752. This explains why the Russian revolution is referred to as the October Revolution, despite occurring in Gregorian November.
- The Julian calendar introduced leap day, but accounted for it by repeating 24 February. The use of 29 February as a leap day wasn’t adopted until the late Middle Ages.
- Full solar eclipses are not rare, but they are very local. On average any given place on the Earth will experience one every 360 years or so.
- Under the most favorable conditions the shadow of a full solar eclipse is a little over 150 miles wide and moves at more than 20 miles per minute for a maximum duration of a little more than 7 minutes.
- The Equinoxes are the only time when the sun passes directly overhead at the equator. So if you were standing on the equator on an Equinox, you would have no shadow.
- There is a persistent myth that you can only balance a raw egg on its end on the Equinoxes. An alternative is that you can never balance an egg on its end. While it’s hard to do, you can balance an egg on any day of the year.
Extra Bonus Fact
Celestial alignments including solstices, equinoxes, and their mid-points or the Celtic cross-quarter days known as Samhain, Imbolc, Beltane, and Lughnasadh. They feature prominently in the Misaligned series. They mark times when the infrastructure of the multiverse is more fragile and interaction between the dimensions more likely.
As always, thanks for reading.
Armen