June 21 2021 – the solstice

This year, the June solstice will fall on 21 June.  In the northern hemisphere, it’s the day when there may be the most daylight and when the Sun is at its highest in the noon sky.

The origin of the phrase solstice is from two Latin phrases:  sol, which suggests Sun, and sistere, to face nonetheless. On the days round  the solstice, the Sun stops getting increased, seems to face nonetheless at the similar peak for just a few days, after which will get decrease in the noon sky.

Solstice Sun El

 

Maximum peak, or elevation, of the Sun, measured in levels above the horizon.. The graph is for a location 50 levels latitude North, which is the similar latitude as the southern tip of the British Isles.  

The incontrovertible fact that the Sun’s elevation modifications steadily means the quantity of daylight additionally modifications little or no round the solstice. This is proven in the desk beneath, which supplies the dawn and sundown instances and the quantity of daylight in hours, minutes and seconds for June in London.

Solstice SR and SS times

Table of dawn and sundown instances for London (supply timeanddate.com  2021).

 

Precise definition of the solstice

Although the solstice is usually to be June 21. There is a extra exact astronomical definition. The diagram above reveals the Earth’s orbit round the Sun. For readability the sizes of the Earth and Sun have been enormously exaggerated.

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Seasons

  • During June, marked A in the diagram, the Earth’s North Pole is tilted in the direction of the Sun and the days are longer in the northern hemisphere.
  • During December, marked C in the diagram, the Earth’s South Pole is tilted in the direction of the Sun and days are longer in the southern hemisphere.
  • At factors Band D, generally known as the equinoxes, neither pole is tilted in the direction of the Sun and the quantities of daylight in the northern and southern hemisphere are equal.

The exact astronomical definition of the June solstice (additionally known as the summer season solstice in the northern hemisphere) is the precise cut-off date when the North Pole is tilted furthest in the direction of the Sun. The instances for this occasion for the years 2021  to 2026 are given in the desk beneath – in UTC (generally identified in the UK as GMT), in Tokyo time (which is 9 hours forward of UTC) and in Hawaiian time (which is 10 hours behind UTC).

Solstice times

As you possibly can see, the time of the solstice varies from year to year and place to position. It can fall on 20, 21 or 22 June, relying in your longitude (and thus your time zone).

Importance of the solstice to early man

The solstice was of nice significance to early man, and lots of prehistoric websites seem to have been constructed to have fun it. The most well-known of those is Stonehenge, which is positioned in Wiltshire, England. It is a set of concentric stone circles constructed between 4000 and 5000 years in the past. It was a tremendous feat of building for stone age man. The stone circle is over 30 metres in diameter. The largest stones are greater than 9 metres tall, weigh over 25 tonnes and had been hauled over 30 km to the website. It is reckoned that the smaller stones had been moved from western Wales, a distance of 225 km (Jarus 2014).

Stonehenge

Image from Wikimedia commons 

At the centre of Stonehenge is a horseshoe association of 5 units of arches known as triliths, every containing three stones.  The open facet of the horseshoe factors North East in the direction of a giant stone 80 metres away from the primary circle. Today this huge stone is given the identify  ‘The Heel Stone’.

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Stonehenge_Heelstone

Image from Wikimedia commons

The monument is organized in such a way that, for just a few days both facet of the June solstice and solely at these dates, somebody standing in the centre of the horse shoe and going through North East will see the Sun rise over the Heel stone.

Heel Stone Sunrise

How dawn at the summer season solstice at Stonehenge would have sorted the monument’s building.

It is wonderful that prehistoric man constructed such a big monument to line up with the June solstice. It clearly should have been a serious occasion for a individuals residing open air with solely pure daylight.  Undoubtedly early man way much more in tune with the pure setting than we’re immediately.

The Solstice immediately

The solstice continues to be celebrated at Stonehenge immediately. Modern teams with historic origins, corresponding to Druids and Pagans, who revere the pure world greater than many trendy people, be part of roughly 30,000 individuals who flock to Stonehenge to observe the Sun rise at the solstice every year.

Interestingly, to stop harm to such an vital historic monument it’s not usually doable to get proper as much as the stones. However, the charity which manages the website English Heritage open it up each year for the solstice, giving individuals  a beautiful alternative

Solstice EH

Image credit score English Heritage

Sadly this  couldn’t occur in 2020 due to the Covid-19 pandemic and at time of writing the plans for the 2021 Summer Solstice celebrations are nonetheless unsure.

The southern hemisphere

To these of you who stay in the southern hemisphere the June solstice is in fact the  winter solstice, when the noon Sun is at its lowest in the sky. After the solstice the days begin getting steadily longer and the nights steadily shorter, though the change doesn’t actually turn into noticeable till July.

Note

It isn’t true that for the total northern hemisphere the noon Sun is at its highest in the sky on the solstice.  This is simply true for location north of the  Tropic of Cancer, (latitude 23.5 levels -shown as the red line beneath). At low latitudes between the equator and the Tropic of Cancer the Sun is instantly overhead at noon on two dates both facet of the solstice. For instance, in San Juan, Puerto Rico, which lies 18.5 levels North of the equator, the Sun is overhead at noon on May 13 and July 30.

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Tropic of cancer

References

Jarus, O (2014) Stonehenge: Facts & Theories About Mysterious Monument, Available at: (*21*)(Accessed: 10 June 2021).

Time and Date (2021 London, ENG, United Kingdom — dawn, sundown, and daylength, June 2018, Available at: http://www.timeanddate.com/sun/uk/london(Accessed: 4 June 2021).

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