THE WINTER SOLSTICE

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Sick of winter? You may be pleased to know the winter solstice is on June 22 this year. However, despite its name, it’s not actually the beginning of the end for those dark mornings.

Some facts . . .

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What exactly is the winter solstice?

The Earth’s axis is tilted – it’s what gives us our seasons, as different parts of the planet are slightly closer to the Sun at different times.

The winter solstice is when we’re tilted the furthest from the Sun (and it’s the summer solstice in the northern hemisphere, because they’re the closest).

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The day of the winter solstice has the least daylight hours of any in the year and usually occurs on 22 June but can occur between 21 and 23 June.

The summer solstice occurs once a year in December when the Sun's track across the Australian sky reaches its highest point. It is the day that has the most daylight hours of any in the year. The summer solstice usually occurs on 22 December, but can occur between 21 and 23 December.

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On the winter solstice, the sunrise is not the latest and the sunset is not the earliest. However, this day does have the least amount of daylight hours.

Likewise, the summer solstice does not feature the day with the earliest sunrise and latest sunset.

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Because the path of the Earth around the Sun is an ellipse, not a circle, and because the Earth is off-centre on its axis, these combined phenomena can create up to several minutes difference between solar and mean time. Around the date of summer solstice, these effects make the Sun appear to move slightly slower than expected when measured by a watch or clock. As a result, the earliest sunrise occurs before the date of the summer solstice, and the latest sunset happens after the summer solstice. For the same reasons, around the winter solstice, the time of sunrise continues to get later in the days after the solstice.

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The Winter solstice is the day of the year when the sun is lowest on the horizon, so that it is the shortest day of the year. As a consequence, the shadows are also the greatest, hence planning applications to local councils require shadow diagrams showing where the shadows will be at 9.00am, midday and 3.00pm on 21 June. Overshadowing of neighbours is a relevant factor to be taken into consideration in whether to approve the development, Councils usually also have codes setting out minimum sunlight for garden and open space areas of the property.

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The word “solstice” originates from the 1st century Roman Latin word “solstitium”, where “sol” meant “sun” and “sister” meant "to come to a stop, make stand still", the point at which the sun appears to stand still.

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The opposite of the solstices are the autumnal and vernal equinoxes, when the Sun is in its zenith over the Equator and the day and night are generally of equal length.’

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Diagram showing Northern hemisphere solstice and equinox dates, reverse them for the Southern hemisphere

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The monthly seasons we use in Australia are skewed to be more closely aligned with our coldest three months than the astronomical seasons.

In Australia June 1 is considered the start of winter.

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Since prehistory, the winter solstice has been a significant time of year in many cultures and has been marked by festivals and rituals. It marked the symbolic death and rebirth of the Sun; the gradual waning of daylight hours is reversed and begins to grow again. Some ancient monuments such as Newgrange, Stonehenge, and Cahokia Woodhenge are aligned with the sunrise or sunset on the winter solstice.

A front view of the Newgrange monument taken from outside the grounds.

Newgrange is a grand passage tomb built during the Neolithic Period, around 3200 BC, making it older than Stonehenge and the Egyptian pyramids. It is aligned on the winter solstice sunrise.

Stonehenge.

Stonehenge is a prehistoric monument on Salisbury Plain in Wiltshire, England. The monument is aligned towards the sunrise on the summer solstice. Archaeologists believe that Stonehenge was constructed from around 3000 BC to 2000 BC.

Cathokia Woodhenge, concrete pylons showing the location of the past timber posts.

The Cahokia Woodhenge was a series of large timber circles located near Collinsville, Illinois. They are thought to have been constructed between 900 and 1100 CE. The site was discovered as part of salvage archaeology in the early 1960s interstate highway construction. The woodhenge is thought by archaeologists to be a solar calendar, capable of marking equinox and solstice sunrises and sunsets for the timing of the agricultural cycle and religious observances.

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The solstice may have been a special moment of the annual cycle for some cultures even during Neolithic times.

Astronomical events were often used to guide activities, such as the mating of animals, the sowing of crops and the monitoring of winter reserves of food.

Many cultural mythologies and traditions are derived from this. The winter solstice was immensely important because the people were economically dependent on monitoring the progress of the seasons. Starvation was common during the first months of the winter, January to April (northern hemisphere) or July to October (southern hemisphere), also known as "the famine months". In temperate climates, the midwinter festival was the last feast celebration, before deep winter began. Most cattle were slaughtered so they would not have to be fed during the winter, so it was almost the only time of year when a plentiful supply of fresh meat was available.

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Northern hemisphere joke