The summer solstice is the longest day of the year, a day falling around late June when there are approximately 17 hours of light.
The name comes from the Latin solstitium meaning “sun stands still”. It happens because the sun stops heading north at the Tropic of Cancer and then returns back southwards.
In the northern hemisphere this means the days begin to get shorter.
But 2016 is a special year, because the solstice coincides with the Strawberry Moon, a once-in-a-lifetime occurence.
The most incredible space images of Earth
The most incredible space images of Earth
1/30 Striking Africa
Explore ESA astronaut Tim Peake's stunning photos of Earth, taken from the International Space Station during his six month mission (captions by Tom Peake)
"The striking colour and texture of Africa Illizi, Algeria"
2/30 Favourite Reef
"Every day spent living in space is a great day, but today was particularly special. I got to speak with one of my inspirational heroes Prof Stephen Hawking and his amazing daughter Lucy, who developed the Principia Space Diary to engage children with STEM subjects. As well as talking about dark matter, quantum entanglement, alien life and light beam powered nanocraft we also got to see an amazing pass over the Bahamas and this - my favourite reef smile emoticon"
3/30 Russia's north-east coast
"Sunrise approaching Russia's frozen north-east coast"
4/30 Hello London
"Hello London! Fancy a run? :) #LondonMarathon"
"50 shades of blue: Bahamas"
"Snow on the mountains next to Yinchuan in China"
7/30 Rocket flames in Africa
"Is it just me or do I see some rocket flames down there? These strange land features are in the Erg Iguidi desert, with its yellow stripes of sand stretching from Algeria to northern Mauritania in the Sahara"
8/30 Stunning colours
"Sunlight reflecting the stunning colours of this Himalayan lake"
9/30 The real Everest
"The real thing: found Everest! Last picture turned out to be third-tallest mountain Kanchengjunga"
10/30 Go Exomars
"Go #Exomars – have a great mission. Earth has more in common with Mars than you might think… #AfricaArt"
"Amazingly clear view of Tenerife"
12/30 Midday winter sun
"Some midday winter sun glinting off Greenland’s snow-capped peaks"
13/30 Sand dunes
"Great texture in these huge sand dunes, Saudi Arabia"
14/30 Dragon Dam
"The dam makes this river look like a dragon’s tail. Oahe Dam north of Pierre, South Dakota in the United States. (North is to the right)"
15/30 Smoking volcano
"Spotted volcano smoking away on Russia’s far east coast this morning – heat has melted snow around top"
16/30 New Zealand
"New Zealand looking stunning in the sunshine. Mt Cook centre left with the Grand Plateau to the front and Mt Tasman (3,497m) to the right of the Grand Plateau. Fox Glacier in the middle then Franz Josef curving right. Tasman Lake (largest at front) is at the foot of the Tasman glacier which runs along the front of them. The Hooker Glacier flows out behind Mt Cook coming down to meet the Mueller Glacier on the left of the photo. The Murchison Glacier is at the front of the photo running parallel with the Tasman Glacier"
17/30 Plankton bloom
"Another great pass over Patagonia and a swirling plankton bloom off the coast"
"We don’t often get such clear views of Alaska"
19/30 Lights along the Nile
"Lights along the Nile stretching into the distance from Cairo"
"The Pacific ‘Ring of Fire’ clear to see amongst the volcanoes of Kamchatka, Russia"
"I’m guessing there was an impressive storm going on under that cumulonimbus cloud"
22/30 Night Sahara
"Night-time Sahara – you can really see how thin the Earth’s atmosphere is in this picture"
"Tokyo and Japanese coast. This image shows most of Japan with the largest mass of light corresponding to Tokyo. The white lights on the left are fishing boats"
24/30 Morning sun volcanoes
"Morning sun striking active volcanoes in Guatemala"
25/30 Tapajos River
"The vast waters of the Tapajos river, Amazonia"
"Beautiful glacial river water flowing from this Patagonian ice field Lake Viedma, West is up"
27/30 Dubai Palms
"Minus the #Dragon photobomb this time..."
28/30 Sediment in Ethiopia
"Sediment spilling into this mountain lake, Ethiopia"
"We have phases of ‘short nights’ on the International Space Station – sunlight is nearly always visible right now. No prizes for guessing where this is…"
30/30 Panama Canal
"From one mighty ocean to another – ships passing through the Panama canal"
What is the Strawberry Moon?
It is a full moon, which occurs in June, named by early Native American tribes. It is a full moon like any other, but marks the beginning of the strawberry season. The two events coincide once every 70 years.
When is the summer solstice?
In the northern hemisphere, it can fall on different dates from year to year, between 20 and 22 June.
In 2016, it's on Monday 20 June. The sun will rise at 4.45am and sunset will happen at 10.34pm.
The winter solstice (the shortest day of the year) falls between 20 and 22 December in the UK. This year it's on 21 December.
Here's a list of the dates and times of solstices and equinoxes this year.
Vernal Equinox (Spring) March 20 2016 04:30 GMT
Summer Solstice (Summer) June 20 2016 22:34 GMT
Autumnal Equinox (Fall) September 22 2016 14:21 GMT
Winter Solstice (Winter) December 21 2016 10:44 GMT
Why is the summer solstice significant?
The summer solstice is a special day for many as it means the start of the summer.
It has links to many ancient cultural practices as different cultures have celebrated it being symbolic of renewal, fertility and harvest.
Why is Stonehenge significant for the solstice?
Stonehenge in Wiltshire is the most popular place in the UK to celebrate the longest day because the prehistoric monument aligns to the solstices. The rising sun only reaches the middle of the stones one day of the year when it shines on the central altar.
It is thought the original builders of Stonehenge had taken giant bluestones from the Preseli Hills in Pembrokeshire to build the inner ring of stones at the monument for reasons that are not fully understood.
The English Heritage-run site is expecting around 20,000 visitors this year.
How to celebrate the summer solstice?
Every year, hundreds of pagans and non-pagans congregate at Stonehenge to see the sun rise in the morning and welcome in the summer.
Some pagans and druids perform a fire ritual to celebrate the occasion. This involves people with unlit candles forming a circle around a large central candle and lighting theirs off it one at a time.
In Sweden, it’s traditional to eat your way through the entire day. Feasts typically involve lots of potatoes and herring.