The Autumnal Equinox 2020

So here we are then. The Autumnal Equinox (in the Northern hemisphere) takes place this afternoon at 14.31 Irish Time (13.31 UT).

Though  the term `equinox’  refers a situation in which day and night are of equal length which implies that it’s a day rather than a specific time, the equinox is more accurately defined by a specific event when the plane defined by Earth’s equator passes through the centre of the Sun’s disk (or, if you prefer, when the centre of the Sun passes through the plane defined by Earth’s equator). Day and night are not necessarily exactly equal on the equinox, but they’re the closest they get. From now on days in the Northern hemisphere will be shorter than nights and they’ll get shorter still until the Winter Solstice.

For many people the autumnal equinox is taken to be the end of summer, though there is a saying around these parts that `Summer is Summer to Michaelmas Day’ (September 29th). Looking back over the posts I’ve written at this time of year since I started blogging in 2008, it’s noticeable how many times we’ve had a window of good weather around the autumnal equinox. In Wales such a warm spell in late September is called Haf Bach Mihangel – “the little summer of St Michael”.

Here’s a sample excerpt from the post I wrote in 2008 on this:

The weather is unsettling. It’s warm, but somehow the warmth doesn’t quite fill the air; somewhere inside it there’s a chill that reminds you that autumn is not far away.

I find this kind of weather a bit spooky because it always takes me back to the time when I left home to go to University, as thousands of fledgling students are about to do this year in their turn.

It has been quite warm here in Maynooth recently too. Last night I mowed the lawn in the evening sunshine, which may well be the last time I do that until spring. The weather turned a bit colder overnight and the weather forecast suggests the little summer may be over.

Anyway, this is Welcome Week in Maynooth and, barring any sudden changes of plan, we’re due to start teaching on Monday 28th September. I’ve been keeping an eye on the registrations of students as they come in as well as starting to get my notes, problem sheets, recordings and other teaching materials together. I have to say that hasn’t been helped by the decision to install a new fire alarm system in the Science Building this week. I had to go home early because of the constant din of the sounders being tested.

I have to admit I’m very apprehensive about the forthcoming semester and beyond. It’s impossible to predict where we will be by the next equinox in March, or even by the Solstice in December. Covid-19 cases are increasing and it doesn’t seem that anyone has a clue how to stop the `second wave’ surging through the population this autumn. The September equinox is often said to to be the start of Astronomical Autumn. This year more than ever it seems to herald that Winter is coming.

One Response to “The Autumnal Equinox 2020”

  1. Here in Melbourne Aus, the equal day was Sunday, 12hrs 0min day/night, Tuesday was 12hrs 4min daylight with equinox at 23:30. “Spring” seen as being 1-sep .. 30-Nov, although the six indigenous seasons better match the climate (mid to late orchid season now), Stay warm & safe as you slide into winter

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