By M. E. Siddall
Next week, Floridians are in for an astronomical treat. Two of them in fact – though it will take some effort and a little lack of sleep to experience both.
The rise of a Supermoon in the East on May 26 at 9:00 pm will be followed by a partial lunar eclipse as the moon sets in the West starting at 5:00 am the next morning. That leaves enough time for the two-hour drive between Miami and Naples and a good 5 hours of sleep as well (which you will need). Sleepless, you can probably just make it in time by riding a bicycle all night. And the moon setting in the West-Southwest at Key Largo should be just as good as Naples.
Humans have been fascinated by the moon for longer than we’ve been able to write about it. The sun is more immediately predictable, rising and setting with daily regularity. Not so for the moon. Contrary to children’s books, sometimes you can see the moon in broad daylight. And unlike the seasonal cadence of the sun, the moon can go from rising in the Northeast to rising in the Southeast in under 10 days.
Cataclysmic Creation
Those fascinating patterns… the cosmic dance of the sun and the moon and a millennia of mythology, cults, poetry and song… they were set on course by a single historical event.
A bit more than four and a half billion years ago, a Mars-sized planet (now called Theia) smacked into Earth with a glancing blow. Most of Theia was incorporated into Earth and gave our Earth an outsized iron core that presently keeps you and me from being baked by cosmic rays from our Sun. Regardless, about 2% of the combined mass of the collision spun off into space and then, congealing under its own weight, began an eccentric elliptical orbital dance around the Earth.
This Is Our Moon
We know much of this because of (yet-another) Canadian-American snow-bird. In 1940, a 15 year-old high school student in Winnipeg bet a friend that we’d have people on the moon within 40 years. Alastair Cameron won that bet, and when, in the early 1970s (10 years ahead of schedule), this astrophysicist looked at Apollo moon rock samples, he intuited the origin not only of the moon, but also of the Earth’s tilt and so much more.
Alastair Cameron solved in a day what had been a mystery for thousands of years.
As you might imagine, everything was rather a mess at first. The Earth was tilted at 70 degrees, spinning wicked-fast (a day was 2 hours) nearly all the way over on its side. And the moon’s orbit was wildly off of the solar system’s axis. But, like a spinning top on a record player, everything started to come back to a central stability. We’re not quite there yet. The Earth is still tilted at 23 degrees (giving us our seasons), a day is now more than 23 hours long, and the moon is no longer at risk of smacking us.
The Moon and the Magic of Measuring
The moon has mostly settled down from the impact. After about 16 million years the moon achieved tidal-lock with Earth. This is why the face of the moon always looks the same, and without which we would not have “Man in the Moon” stories (or “Rabbit in the Moon” stories south of the Equator). But the moon’s orbit remains elliptical and is still at a 5 degree inclined tilt.
That tilt is in fact the magic in the moon.
Had the moon settled into its yet-to-be-achieved final orbit before humans existed, we would have been hard-pressed to figure out latitude, cartography and may not have bothered with computers at all. In its final orbit – in line with the plane of the solar system – there would have been a lunar eclipse every month with every full moon, and a solar eclipse every month with every new moon.
Such once-a-month monotonous occurrences would hardly have carried omens for the Siege of Syracuse (28 BCE), much less the deaths of Herod, Augustus and possibly Christ himself.
Earth’s tilt made measuring longitude a breeze. But latitude was terrifically difficult without knowing how big around the Earth might be. From the 1600’s onwards this proved increasingly important to European powers that were busy carving up the planet into their own colonial bits.
The genius was finding a regularity in what was only seemingly irregular. The irregularity was made-so by the tilt of the Earth and the inclination of the moon’s orbit. Some very good math (calculus) developed by Sir Isaac Newton allowed for historical decombobulation. But like any modern artificial intelligence app, the decombobulation of latitude needed input parameters.
Enter Captain James Cook.
The Moon and the Mechanism
Notwithstanding all of the other exploratory achievements of Captain Cook’s voyages, the point of those voyages was to witness eclipses. Whether it was off of the coast of Newfoundland bludgeoning and eating the last of the Great Auk, or the day he nearly died eating fugu in New Caledonia, Cook was there to witness and measure eclipses. These were the input data for the decombobulation A.I. of the day.
But Cook wasn’t the first. We now know that this was the cause of the very first computer ever – the Antikythera Mechanism.
Among the wreckage retrieved from a shipwreck off the coast of the Greek island Antikythera in 1901 was a mechanism full of gears. But the unusual number of teeth on the gears and the arrangement of the gears made no immediate sense. There was no obvious use on a Byzantine era ship dated to approximately 70–60 BCE. It looked like clockwork, but was far too complicated to just be a clock.
For a century, the Antikythera wreck has inspired marine archaeologists like Brendan Foley and Phil Short who have now mapped it with modern imaging technology. In large part, this is due to the obvious technological feats inherent in the Antikythera mechanism itself. In 2014, Michael Wright recreated a complete Antikythera mechanism from scratch. The Antikythera mechanism was the world’s first super computer made to decombobulate among other things… latitude. The gears are the data input from the progress of the sun and the moon, their ellipses and their eclipses. It was all done to be able to figure out the most fundamental human question:
Where am I?
Illumination and Illusion
Much of the foregoing has been about the partial lunar eclipse you can witness from Naples Florida starting about 5 am on May 27. For a total lunar eclipse and a blood red moon, you will have to fly to Australia or New Zealand and hope for good weather.
The redness of the moon in a lunar eclipse would never be seen had Earth no life sustaining atmosphere. The moon would merely appear to disappear during a lunar eclipse. With an atmosphere, and the Sun behind the Earth, enough low energy (red) light makes it through our fringing atmosphere to light up the moon to a blood-red color, even when no sun can hit it directly. High energy photons in the blue spectrum are scattered.
The creepy and foreboding effect is why watching the moon set on the Gulf Coast of Florida on the morning of May 27 is worth the trip. No, it won’t be a total lunar eclipse. But the moon will be over 60 percent in the umbra with the rest penumbral, and it will look plenty creepy. Especially after that super-bright Supermoon rising in the East a few hours before.
A Blue moon is a second full moon in a calendar month. Being somewhat uncommon (the last one was this past Halowe’en), they occur only “once in a Blue moon”. The next one will be August 2023. The Harvest moon isn’t just a Neil Young masterpiece, it’s an autumnal full moon that gave farmers enough light by which to keep harvesting into the night. The full moon in May is sometimes called the Flower moon, but to the Seminole it was the Mulberry moon.
What then is a Supermoon?
As a result of the speed and angle with which Theia smacked into Earth, the bits that flew off and became the Moon don’t circle the Earth in an actual circle. It’s an oval… an ellipse. Think of it as a wobble. If you make bread or pizza dough with a Kitchen-Aid you will completely understand. Sometimes the moon is closer to the outer edge, and sometimes it’s closer to the middle. But it’s never in the same place from day to day.
If you compared a photo of the moon at apogee (furthest away) to a photo of the moon at perigee (May 26), you could measure that there is about a 15% difference in apparent diameter.
But here’s the thing… at that distance and size, the human eye is known to be incapable of perceiving any difference. We’d be hard-pressed to notice it even if apogee and perigee moons were side by side which they never are.
But we do notice. And anyone who tells you that you are imagining things is wrong. Even though they are right.
A Supermoon at perigee is not close enough for you to detect a difference in size, but the change in distance increases the moon’s brightness according to the inverse-square law. If the moon changed distance by a half, it would look four times brighter. That would be huge (and tides would be terrible). So although the apparent diameter change of the moon is imperceptible, like the halogen headlights of a car behind you on high-beam, the moon legitimately will look bigger on May 26, because it will be that much brighter.
The Grand Illusion
I began this post noting that humans have been fascinated by the moon for longer than we’ve been able to write about it. We are a product of our evolutionary history. We have, in us, hard-wired perceptions of our environment and our experience. This is not just an innate fear of snakes, it is also an innate relationship to spatial perception, and to the moon.
The most compelling astronomical event of May 26/27 is not the partial lunar eclipse on the Gulf Coast, but the Supermoon and the moon Illusion on the East coast starting at 9 pm on May 26. Unlike a sunrise or sunset, and for reasons not fully understood, your prehistoric remnant of an early human brain will kick in, in a glorious and unexplained psychological way. This is especially so if you watch the moon rise from West side of Biscayne Bay, not from Miami Beach.
With recognizable objects like the buildings and landscape of the islands and keys between you and the horizon, your brain will overestimate the size of the rising moon. This phenomenon is a universal illusion. You can test it yourself by putting your smartphone on a photo-time-lapse as you witness the rising of the moon. Or, when the moon looks enormous, pick up a small pebble and easily obscure it. But beware, this will ruin the beauty of the illusion.
Setting aside the mundaneness of the fact that the moon (to a camera) will always look the same size, it is truly a deeply meaningful and very human experience that the rising of the moon can appear ten times bigger and ten times more impressive under the right conditions. It is the same sensation that keeps us from getting too close to edges when those edges are far away from the ground below.
That illusion is universal. The most studied astrophysicist also experiences the Supermoon phenomenon the same way you do, even though they know the truth. Knowledge of the truth does not diminish the illusion. She does so in the same child-like wonder as a 5 year old snuggling under a blanket in Ferré Park next week after visiting and getting pointers from the education staff at the Frost Museum of Science. That’s actually a very good place to witness the moonrise of a Supermoon.
We have spent the entirety of our species’ duration learning and studying our planet, our moon, and our relationship to our cosmos… and yet we remain instinctually in awe.
We cannot help ourselves but be enamoured… and moved.
Experience as precious as knowledge
There is no amount of knowledge that will make this less magical or experiential. Our knowledge and mastery of math and science only makes our perception of our world ever-the-more mystical and meaningful for what cannot yet be readily understood or explained.
Some will not bother with the Supermoon rise of May 26. Maybe even most will not bother with its eclipse.
But for me, I cannot let this pass by.
As Paul Bowles wrote in “The Sheltering Sky”
Everything happens a certain number of times, and a very small number, really. How many more times will you remember a certain afternoon of your childhood, some afternoon that’s so deeply a part of your being that you can’t even conceive of your life without it? Perhaps four or five times more. Perhaps not even.
How many more times will you watch the full moon rise?
