The summer solstice is being observed worldwide and in the US on Sunday,  June 20. Starting at 11.32 pm EDT, the day will be observed as the first day of summer and the longest day of the year. The first day of summer is called the longest day because the day has the most daylight as compared to other days.

The summer solstice is the day when the sun travels the longest through the sky and reaches its highest point. The day is observed in many forms around the world. 

On this day, the North Pole is shifted towards the sun because Earth’s axis is tilted in that way, thus, it results in the long hours of daylight, Britannica.com said. 

While Summer solstice occurs between June 20-22 in the Northern Hemisphere, it occurs on December 21-22 in the Southern Hemisphere. 

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Summer and winter solstices have for centuries guided people in knowing the position of the sun at specific times and it indicates people in practicing traditions or rituals or in knowing when it is the right time to plant or harvest crops.

According to Scientific American, the summer and winter solstices were used by the Mayans and Aztecs as markers to build structures that lined up with the shadows created by the sun. The summer solstice was also used to mark as an official one-month countdown for the Olympics, according to History.com. 

The summer solstice is recognised with a Sun Dance by many native American tribes.