In pictures: Swimmers and hikers enjoy solstice

Summer solstice is being celebrated across the northern hemisphere, marking the start of astronomical summer.

While we generally think of it as the whole day, it actually happens at a single moment when the hemisphere's pole is tilted at its maximum angle towards the sun.

That exact time this year is Sunday 21 June at 09:24 BST.

Its significance is reflected at monuments and in rituals around the world.

We have selected some images from across the UK to mark the event.

The solstice always occurs between 20 and 22 June, though during a leap year it generally falls on 20 June.

The exact date shifts slightly each year because the Earth takes almost a quarter of a day longer to complete its orbit of the sun than our calendar accounts for.

This discrepancy is why we add a leap day every four years – to keep the calendar aligned with Earth's orbit.

In English, the world solstice comes from the Latin word solstitium, meaning "sun standing still".

It seems to suggest a brief pause as the sun reaches its most extreme point.