Wrapped in jackets and blankets, thousands of people gathered at Britain's Stonehenge for summer solstice, watching the sun rise over the Neolithic monument and welcoming the longest day of the year.
The Druid and Pagan community perform rituals and celebrations at the summer and winter solstices.
On the summer solstice, 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.
According to Dr Bashir Marzouk, astronomer at the Qatar Calendar House, the summer solstice and the rest of the four astronomical seasons occur as a result of the rotation of the Earth around the Sun, in addition to the axis of the Earth at the level of its orbit at an angle of 23.5 degrees.
What is the summer solstice?
It brings the longest day and shortest night of the year for the 88 percent of Earth's people who live in the Northern Hemisphere.
Up to 25,000 people were expected to attend the overnight celebration of the longest day of the year at the World Heritage Site.
The solstice is the 24-hour period during the year when the most daylight hits the Northern Hemisphere. Even that's an approximation - Earth's atmosphere bends light over the horizon by different amounts depending on weather, which can introduce changes of more than a minute to sunrise and sunset times.
In the United Kingdom, the Stonehenge monument - an UNESCO World Heritage Site - will be open to visitors.