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Summer solstice

Bubbles float past as revellers watch as the midsummer sun rises just after dawn over the megalithic monument of Stonehenge on June 21, 2010 on Salisbury Plain, England. Thousands of revellers gathered at the 5,000 year old stone circle to see the sunrise on the Summer Solstice, which is the longest day of the year in the Northern Hemisphere. (Photo by Matt Cardy/Getty Images)

Summer solstice

The summer season for Earth's Northern Hemisphere officially began on June 21. In England, more than 20,000 celebrants gathered at the famed Stonehenge monument to mark the day.