The summer solstice is an astronomical term regarding the position of the sun in relation to the celestial equator. At the time of the summer solstice, Earth is at a point in its orbit where one hemisphere is most tilted towards the sun, causing the sun to appear at 23.45 degrees above the celestial equator, thus making its highest path across the sky.

The summer solstice is the day of the year with the longest daylight period and hence the shortest night. This day usually occurs on June 21/June 22 in the northern hemisphere and on December 21/December 22 in the southern hemisphere. The actual date changes due to differences between the calendar year and the tropical year.