The Autumnal Equinox (in the Northern hemisphere) takes place this afternoon (Sunday 22nd September 2024) at 13.44 Irish Summer Time (12.44 UT).
Although the term `equinox’ refers to a situation in which day and night are of equal length, which implies that it’s a day rather than a specific time, the astronomical equinox is more accurately defined by a specific event, i.e. 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 on 21st December 2024 at 9.21am Irish Time.
Many people take the autumnal equinox to be the end of summer. There is a saying around these parts, however, that `Summer is Summer to Michaelmas Day’ (September 29th), which is not until next week. I must say, though, though it doesn’t feel particularly summery this morning although we did have good weather for most of last week. Looking back over my posts on past occurrences of the Autumnal Equinox, it is notable how many talk about a period of good weather around this time of year. The Welsh phrase Haf Bach Mihangel (Michael’s Little Summer) refers to this kind of spell.
I’ve often remarked how the academic year at Maynooth is largely defined by the astronomical phenomena of the equinoxes and solstices. This year demonstrates this perfectly: Semester 1 lectures for undergraduates begin tomorrow (23rd September), the day after the Autumnal equinox; they end on 20th December, the day before the Winter Solstice. The half-term study break coincides with Samhain, a cross-quarter day. It’s all refreshingly pagan.
This time last year I was getting ready to travel to Barcelona. My sabbatical started on 1st September but I didn’t actually leave for Spain until 24th September. That all seems a very long time ago now, and my sabbatical is well and truly over. I resume teaching next week, though my first lectures (a double session of Engineering Mathematics) are not until Tuesday. I hope I can remember how to teach! I’m also doing Differential Equations and Complex Analysis for 4th Year Mathematical Physics students, but the lectures for that are a bit later (Thursday and Friday). I have taught neither of these modules before, so I am a bit apprehensive.
I now know what I’ll be teaching next Semester too. I’m returning to Computational Physics 1, which I taught for 5 years before my sabbatical, so that’s a familiar one. I’m also doing Particle Physics for 4th year students. I taught a full module in that at Nottingham and a half-module in Cardiff so it’s not exactly new but I haven’t lectured in the subject since about 2010. Has anything important happened in that field since then? I assume that had there been, for example, any new boson discovered I would have heard about it…
In the Dark 