Eclipses
and the grander cycles of our planet, sun and moon
Dear word explorer,
September is strumming its mellow vibe in Ireland. Once again: skip coming to Ireland in August, go for the fringe months of May/June or September. August is always temperamental, and sometimes that crankiness sets in during July. Good weather arrives in the Emerald Isle when you don’t demand it. Sadly, this quixotic schedule does not coincide with school holidays — you have to adjust your expectations and enjoy the heck out of the sunshine when it graces us with its erratic presence.
Our maxed out sun is flinging Coronal Mass Ejections (CMEs or expulsions of plasma and magnetic field from the Sun’s corona) like hot streamers across the solar system. Venus, Mercury and Mars have been bombarded, along with Earth. Luckily, unlike our nearest neighbors, Earth has a robust magnetosphere which (mostly) absorbs the energy and offers us beautiful light displays.
Here’s a fun factoid I’ve discovered: ‘CMEs often look like huge, twisted rope, which scientists call ‘flux rope’.’1
Just imagine those sizzling flux ropes speeding their way to our planet!
Check out this X4.5-class solar flare from 14 September 2024, which was accompanied by a significant CME and provoked a G4-class (Severe) geomagnetic storm last night across parts of the upper northern hemisphere, resulting in impressive aurora lightshows.2
Expect more of this from our tempestuous sun, but tonight we’re going to experience a gorgeous full ‘Super Harvest’ moon, which will be stunning if you have clear skies, but its luminous glow may inhibit sightings of northern lights.
And we’re getting a partial lunar eclipse!
‘Lunar eclipses occur at the full moon phase. When Earth is positioned precisely between the Moon and Sun, Earth’s shadow falls upon the surface of the Moon, dimming it and sometimes turning the lunar surface a striking red over the course of a few hours. Each lunar eclipse is visible from half of Earth.’3
This occultation occurs due to the symmetrical ratios of the sun and the moon in relation to Earth. The Sun is 400 times bigger than the Moon, but the Moon is 400 times closer to Earth than the Sun.
Eclipses always occur in pairs two weeks apart (and every six months) so the corresponding solar eclipse will occur on the 2nd of October. In that case the Moon interposes between the Earth and the Sun.4
Did you know that eclipses are part of millennial-long cycles?
First, I’ll have to explain a few terms.
A ‘synodic month’ is a fancy way of saying a lunar month, and it comes from the Greek synodikós, which translates as ‘pertaining to a synod’, and a synod is a meeting. What’s so sweet about this expression is that it conjures the image of the Earth and the Moon having a get-together. Since I’m an animist at heart, this description of each lunar month as being a conversation between the Earth and the Moon is endearing. They have their back and forth, one of them buys lunch and the other one brings a bunch of flowers.
From our Earth-bound point of view, each synodic month lasts approximately 29 days, 12 hours, 44 minutes and 2.9 seconds. But the moon’s orbit is not straightforward, it likes to mix things up. The shape of its orbit means that sometimes it is closer or further away from Earth: if you track it from perigee to perigee, you get the anomalistic month. It also drifts a little above and below the ecliptic path and only intersects at two points during a cycle, and measuring this interaction is referred to as the draconic month.
The combination of these three factors means that eclipses are part of a pattern known as the ‘saros cycle’. Each one repeats every 6,585.3 days (or 18 years, 11 days and 8 hours). This is not a new discovery. The pattern was recorded long ago by our observant ancestors, who had a much deeper connection to the starry skies (since they didn’t deal with light pollution). As far back as the 8th and 7th centuries BC, Babylonian astronomers began making and recording precise measurements. Over time they noticed similarities in lunar eclipses every 18+ years or so (the Greeks later referred to these early astronomers as Chaldeans).
Tonight’s eclipse is part of saros 118, which began back on 2 March 1105! The final iteration of this lunar eclipse cycle will be 7 May 2403.
It is complicated, so this useful graphic from NASA demonstrates the progression using the example of solar eclipse cycle, saros 136.
As you can see, each saros cycle eclipse path shifts about 120 degrees west of the previous iteration. If you created an animation for each cycle they would look like a sinewy shadow winding around the globe — until they disappear!
I hope this wasn’t too info-dense. It’s taken me a while to absorb it completely, and I’m also trying not to get too bogged down in technical details.5
But when I emerged from the mist of facts and figures, what entranced me was the beauty of this ancient dance between the Earth, Moon and Sun.
Just imagine, on 2 March 1105 our ancestors looked up at the first lunar eclipse in this cycle, and here we are, enjoying it in 2024. Our descendants will continue to observe it every 18+ years until 7 May 2403.
Also consider: ‘A saros series lasts between 1,226 and 1,550 years and comprises 69 to 87 eclipses. As one series ends, another is born. On average, 42 series are running in parallel at a given time.’6
We inhabit an incredible cosmos! When things feel awry and difficult, it’s good to take a step back and remember that all things change and shift even with long-lasting cycles. We are part of a complex cosmic weave, and each of us have a part to play in it.
Keep watching the skies!
‘Coronal Mass Ejections on the Sun’ via NASA’s JPL website.
As always, spaceweather.com is your go-to web site for current sun-related information.
I discussed solar eclipses just before the big one in April this year, and the mythology around eclipses in the subsequent newsletter.
There are plenty of resources about this online if you want a thorough explanation. A great start is this video on the YouTube channel, Slide Rules and Mathematics.
Informative
Definitely feeling the push and pull of the time vortices at the moment!