Archive for Spring Equinox

The Vernal Equinox 2025

Posted in Biographical, Maynooth, The Universe and Stuff with tags , , on March 20, 2025 by telescoper
Loughcrew Cairn: for a few days on and around the vernal equinox the rays of the rising Sun penetrate the passage and illuminate the back stone.

Just a quick note to mention that the Vernal Equinox (Spring Equinox) in the Northern hemisphere happens this morning, Thursday 20th March 2025, at 9.01 UTC (which is 9.01am local time here in Ireland, i.e. in about half an hour). Many people in the Northern hemisphere regard the Vernal Equinox as the first day of spring; of course in the Southern hemisphere, this is the Autumnal Equinox.

The date of the Vernal Equinox is often given as 21st March, but in fact it has only been on 21st March twice this century so far (2003 and 2007); it was on 20th March in 2008, has been on 20th March every spring from then until now, and will be until 2044 (when it will be on March 19th).

Anyway, people sometimes ask me how one can define the `equinox’ so precisely when surely it just refers to a day on which day and night are of equal length, implying that it’s a day not a specific time? The answer is that the equinox is defined by a specific event, the event in question being 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 until the Autumnal Equinox, days in the Northern hemisphere will be longer than nights, and the days will continue get longer until the Summer Solstice before beginning to shorten again.

P.S. This time last year I was in Barcelona. Time passes.

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The Vernal Equinox 2024

Posted in Barcelona, The Universe and Stuff with tags , , on March 20, 2024 by telescoper

Loughcrew (County Meath, Ireland), near Newgrange, an ancient burial site and  traditional place to observe the sunrise at the Equinox

Just a quick note to mention that the Vernal Equinox, or Spring Equinox, (in the Northern hemisphere) took place today, Wednesday 20th March 2024, at 3.06 UTC (which was 4.06am CET, where I am at, though I was sound asleep at the time). Many people in the Northern hemisphere regard the Vernal Equinox as the first day of spring; of course in the Southern hemisphere, this is the Autumnal Equinox.

The date of the Vernal Equinox is often given as 21st March, but in fact it has only been on 21st March twice this century so far (2003 and 2007); it was on 20th March in 2008, has been on 20th March every spring from then until now, and will be until 2044 (when it will be on March 19th). This year the equinox happened before dawn, so sunrise this morning could be taken to be the first sunrise of spring. It felt more like summer, sipping coffee on my terrace in Barcelona:

This reminds me of a strange conversation I had on a plane recently. I was chatting to the person sitting next to me, who happened to be British. When he asked what I did for a living, I replied that I was an astrophysicist. He then complained that he preferred the old days when the Spring Equinox was on March 21st, and that now that Britain was out of the European Union he hoped it would change back…

Anyway, people sometimes ask me how one can define the `equinox’ so precisely when surely it just refers to a day on which day and night are of equal length, implying that it’s a day not a specific time?

The answer is that the equinox is defined by a specific event, the event in question being 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 until the Autumnal Equinox, days in the Northern hemisphere will be longer than nights, and they’ll get longer until the Summer Solstice before beginning to shorten again.

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The Vernal Equinox 2023

Posted in Biographical, The Universe and Stuff with tags , , , , , on March 20, 2023 by telescoper

The Vernal Equinox, or Spring Equinox, (in the Northern hemisphere) takes place on Monday 20th March 2023, at 21.24 UTC (which is this evening at 9.24pm local Irish Time). I’m posting this 12 hours in advance of the big event to give you plenty of notice.

Many people regard the Vernal Equinox as the first day of spring; of course in the Southern hemisphere this is the Autumnal Equinox. The date of the Vernal Equinox is usually given as 21st March, but in fact it has only been on 21st March twice this century so far (2003 and 2007); it was on 20th March in 2008, has been on 20th March every spring from then until now, and will be until 2044 (when it will be on March 19th). This year, however, the Sun will already have set in Ireland before the Equinox, so sunrise tomorrow 21st March could reasonably be taken to be the first dawn of Spring.

People sometimes ask me how one can define the `equinox’ so precisely when surely it just refers to a day on which day and night are of equal length, implying that it’s a day not a specific time?

The answer is that the equinox is defined by a specific event, the event in question being 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 until the Autumnal Equinox, days in the Northern hemisphere will be longer than nights, and they’ll get longer until the Summer Solstice before beginning to shorten again.

Loughcrew (County Meath), near Newgrange, an ancient burial site and a traditional place to observe the sunrise at the Equinox

There’s usually a lot of neo-Pagan nonsense going around at the Solstices and Equinoxes, which reminded me of the following clipping related to an even more significant astronomical event, a total eclipse. I found it in The Times, in 1999, just before the total eclipse that was visible from parts of the United Kingdom on August 11th of that year. It was a feature about the concerns raised by certain residents of Cornwall about the possible effects of the sudden influx of visitors on the local community. Here is a scan  of a big chunk of the story, which you probably can’t read…

.and here is a blow-up of the section shown in the red box, which places cosmologists such as myself in rather strange company:

In protest, I wrote a letter to the The Times saying that, as a cosmologist, I thought this piece was very insulting … to Druids. They didn’t publish it.

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The Vernal Equinox 2022

Posted in Maynooth with tags , , , on March 20, 2022 by telescoper

Just a quick note to say that the Vernal Equinox, or Spring Equinox, (in the Northern hemisphere) takes place this afternoon at 15.33 UTC (which is 3.33 pm local Irish Time). Many people regard this as the first day of spring. The weather in Maynooth is certainly spring-like. Of course in the Southern hemisphere this is the Autumnal Equinox.

The date of the Vernal Equinox is usually given as 21st March, but in fact it has only been on 21st March twice this century so far (2003 and 2007); it was on 20th March in 2008, has been on 20th March every spring from then until now, and will be until 2044 (when it will be on March 19th).

People sometimes ask me how one can define the `equinox’ so precisely when surely it just refers to a day on which day and night are of equal length, implying that it’s a day not a specific time?

The answer is that the equinox is defined by a specific event, the event in question being 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 until the Autumnal Equinox days in the Northern hemisphere will be longer than nights, and they’ll get longer until the Summer Solstice before beginning to shorten again.

Loughcrew (County Meath), near Newgrange, an ancient burial site and a traditional place to observe the sunrise at the Equinox

Here in Ireland we celebrated Saint Patrick’s day on March 17th, the reputed date of his death in 461 AD. Although he may have been born in Wales, nobody really knows for sure precisely where St Patrick was born, though, so it would be surprising if the when were any better known.

In any case, it wasn’t until the 17th Century that Saint Patrick’s feast day was placed on the universal liturgical calendar in the Catholic Church. In the thousand years that passed any memory of the actual date was probably lost, so the Equinox was perhaps rebranded for the purpose.

The early Christian church in Ireland incorporated many pre-Christian traditions that survived until roughly the 12th century, including the ancient festival of Ēostre (or Ostara), the goddess of spring associated with the spring equinox after whom Easter is named. During this festival, eggs were used a symbol of rebirth and the beginning of new life and a hare or rabbit was the symbol of the goddess and fertility. In turn the Celtic people of Ireland probably adapted their own beliefs to absorb much older influences dating back to the stone age. St Patrick’s Day and Easter therefore probably both have their roots in prehistoric traditions around the Spring Equinox, although the direct connection has long been lost.

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The Vernal Equinox 2021

Posted in History, Maynooth with tags , , , , on March 20, 2021 by telescoper

It is 9.37am Local Time in Ireland on Saturday 20th March 2021 which means that the Vernal Equinox or Spring Equinox (in the Northern hemisphere) is taking place right now!

The Spring Equinox jumped back a day last year because 2020 was a leap year and now is gradually moving forward again. Of course the actual date depends on where you are in the world. The date last year was 20th March (early in the morning) in Ireland, but 19th March (late at night) in New York.

People sometimes ask me how one can define the `equinox’ so precisely when surely it just refers to a day on which day and night are of equal length, implying that it’s a day not a specific time?

The answer is that the equinox is defined by a specific event, the event in question being 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 until the Autumnal Equinox days in the Northern hemisphere will be longer than nights, and they’ll get longer until the Summer Solstice before beginning to shorten again.

Loughcrew (County Meath), near Newgrange, an ancient burial site and a traditional place to observe the sunrise at the Equinox

Here in Ireland we celebrated Saint Patrick’s day on March 17th, the reputed date of his death in 461 AD. Nobody really knows where St Patrick was born, though, so it would be surprising if the when were any better known.

In any case, it wasn’t until the 17th Century that Saint Patrick’s feast day was placed on the universal liturgical calendar in the Catholic Church. In the thousand years that passed any memory of the actual date was probably lost, so the Equinox was perhaps rebranded for the purpose.

The early Christian church in Ireland incorporated many pre-Christian traditions that survived until roughly the 12th century, including the ancient festival of Ēostre (or Ostara), the goddess of spring associated with the spring equinox after whom Easter is named. During this festival, eggs were used a symbol of rebirth and the beginning of new life and a hare or rabbit was the symbol of the goddess and fertility. In turn the Celtic people of Ireland probably adapted their own beliefs to absorb much older influences dating back to the stone age. St Patrick’s Day and Easter therefore probably both have their roots in prehistoric traditions around the Spring Equinox, although the direct connection has long been lost.

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The Vernal Equinox 2020

Posted in History, Maynooth with tags , , , , on March 20, 2020 by telescoper

With everything else going on I quite forgot that the Vernal Equinox or Spring Equinox (in the Northern hemisphere) took place today (Friday 20th March) at 3.49am (Irish Time). This is in fact the earliest Spring Equinox for 124 years, the fact that 2020 is a leap year moving it a day earlier in our calendar. It’s a lovely day in Maynooth too!

People sometimes ask me how one can define the `equinox’ so precisely when surely it just refers to a day on which day and night are of equal length, implying that it’s a day not a specific time?

The answer is that the equinox is defined by a specific event, the event in question being 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 until the Autumnal Equinox days in the Northern hemisphere will be longer than nights, and they’ll get longer until the Summer Solstice before beginning to shorten again.

Loughcrew (County Meath), near Newgrange, an ancient burial site and a traditional place to observe the sunrise at the Equinox

Here in Ireland we celebrated Saint Patrick’s day on March 17th, the reputed date of his death in 461 AD. Nobody really knows where St Patrick was born, though, so it would be surprising if the when were any better known.

In any case, it wasn’t until the 17th Century that Saint Patrick’s feast day was placed on the universal liturgical calendar in the Catholic Church. In the thousand years that passed any memory of the actual date was probably lost, so the Equinox was perhaps rebranded for the purpose.

The early Christian church in Ireland incorporated many pre-Christian traditions that survived until roughly the 12th century, including the ancient festival of Ēostre (or Ostara), the goddess of spring associated with the spring equinox after whom Easter is named. During this festival, eggs were used a symbol of rebirth and the beginning of new life and a hare or rabbit was the symbol of the goddess and fertility. In turn the Celtic people of Ireland probably adapted their own beliefs to absorb much older influences dating back to the stone age.

St Patrick’s Day and Easter therefore probably both have their roots in prehistoric traditions around the Spring Equinox, although the direct connection has long been lost.

1 Comment »