MANILA, Philippines—After today, the nights will be longer and the days will be shorter, according to the Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa).

In its astronomical diary for September, Pagasa said the autumnal equinox is expected to occur on Wednesday—this is when day and night are approximately equal in length.

“The Sun’s declination is zero degrees and there are 12 hours of day and 12 hours of night at all points on the Earth’s surface. The noon altitude of the Sun is 90 degrees (the zenith) at the equator and diminishes to zero degrees at the poles,” Pagasa said.

But from Sept. 24 to March 20 next year, nights will be longer than days as the sun lies south of the celestial equator or the imaginary horizontal line running in the middle of the earth.

This signifies the approach of winter in the northern hemisphere and summer in the southern hemisphere.

In the northern hemisphere and in China, the autumnal equinox is also called “Harvest Home,” a holiday and thanksgiving for the fruits of land.

In Japan, the autumnal equinox is called Higan, an official holiday where families visit the graves of their loved ones.