What is the summer solstice?

Thousands of people are expected to mark the summer solstice by watching the sun rise over Stonehenge.

Revellers will gather at the neolithic Wiltshire monument on Wednesday, 21 June to celebrate the longest day of the year.

Here is everything you need to know about the summer solstice.

What is the summer solstice?

The summer solstice, also known as midsummer, falls between 20 and 22 June every year in the northern hemisphere. It occurs on the day when the sun reaches its highest position in the sky, ensuring the longest period of daylight of the year.

The word 'solstice', which originates from Latin, means a stopping or standing still of the sun. The winter solstice, the shortest day of the year, falls between falls between 20 and 21 December.

Why do people gather at Stonehenge?

The summer solstice is an important occasion for druids and pagans who, for thousands of years, have gathered at Stonehenge to perform rituals.

The ancient stone circle is built along the solstice alignment of the summer sunrise and the winter sunset.

The sun rises behind the Heel Stone, the ancient entrance to the stone circle, and rays of sunlight are channelled into the centre of the monument.

The landmark, which dates from about 2500 BC, is thought to have served an ancient solar calendar, helping people to keep track of the days, weeks and months.

English Heritage historian Susan Greaney said: "For neolithic people, sunlight would have been crucial – for warmth for them and their animals and for helping their crops to grow.

"It would have been relatively easy for prehistoric people to observe the rising and setting positions of the sun each day, and to mark these orientations from any given spot. It must have been important to align their monument with the movements of the sun but we may never know the exact reasons why.

"The longest day of the year would have perhaps been a time of celebration, with warm nights and long daylight making it the perfect time to gather together."