What is the summer solstice and how many hours of daylight is there?
Its thought Stonehenge could have been built to mark the solstice (Picture: Getty)  Happy Solstice! Today, 21 June, marks the Summer Solstice 2021 which means that summer is officially here. The day has a long history, having been traditionally celebrated by Wicca, Pagans and Christians. The longest day of the year was also used by ancient Greeks to calculate the size of the earth. In the northern hemisphere, the summer solstice, or longest day of the year, takes place between June 20 and 22 each year, this year falling on June 21. The date marks the beginning of summer (Picture: Getty)  It occurs when the tilt of Earths axis is most inclined towards the sun and is directly above the Tropic of Cancer. It officially marks the beginning of the astronomical summer, which ends with the autumn equinox in September. The UK is expected to enjoy 16 hours and 39 minutes of daylight on this years solstice. The sun will rise at 4.43am and set at 9.22pm, but its likely to be overcast in most parts of the UK. There are two solstices each year  a summer and a winter solstice. Each year, many druids, pagans and Wicca visit stone circles and wait for the sun to appear. English Heritage warned people not to attend Stonehenge or similar structures this year, to prevent large crowds. They planned to live stream the sunrise from Stonehenge, but this was cut short due to public interference at the stones. English Heritage cut short this years live stream because of people at the stones (Picture: Getty)  Historically, the summer solstice period used to fall between the planting and harvesting of crops, leaving people who worked the land time to relax. Every planet has a summer solstice. On Mars (our closest planet), the longest day of the year takes place a few days later. MORE : Summer solstice: Facts to celebrate the longest day of the year  Follow Metro across our social channels, on Facebook, Twitter and Instagram  Share your views in the comments below