The annual summer solstice, which marks the year’s longest dayand shortest night, will occur this Monday.

The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) said that days get longer in the Philippines due to summer solstice, an astronomical term regarding the position of the sun in relation to the celestial equator.

The summer solstice is the day of the year with the longest daylight period and hence the shortest night, which usually occurs on June 21 or June 22 in the northern hemisphere.

For this year, summer solstice falls exactly at 1:16 p.m. on June 21 (Philippine time).

This is the time when the sun attains its greatest declination of +23.5 degrees and passes directly overhead at noon for all observers at latitude 23.5 degrees north, which is known as the Tropic of Cancer, PAGASA said.

For some people, the solstice marks the start of summer in the northern hemisphere and winter in the southern hemisphere, particularly in countries experiencing four seasons in a year.

Wikipedia defines a solstice as “an astronomical event that happens twice each year — the summer and winter solstices.”

It occurs when the tilt of the Earth's axis is most inclined toward or away from the Sun, causing the Sun's apparent position in the sky to reach its extreme northernmost or southernmost position. (Ellalyn B. De Vera)