Why day and night have 'nearly' the same length on March 20
'March equinox' is one of the two occasions throughout the year when day and night are almost equal in length
On March 20, an astronomical phenomenon, known as the “vernal equinox,” will occur when the Sun is directly overhead the Earth’s equator, making day and night “nearly equal” in length.
In its monthly astronomical diary, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) said the vernal equinox—also known as the March equinox—marks the first day of spring for those in the northern hemisphere and the first day of autumn for those in the southern hemisphere.
“During equinoxes, the Sun directly points over the Earth’s equator, thus creating nearly equal day and night. Also, on this day, the Sun exactly rises due east and sets due west,” PAGASA said.
The Sun will be exactly above the equator at 11:06 a.m. (Philippine time) during the vernal equinox.
The Philippines will see the sun rise at 6 a.m. and set at 6:06 p.m., making the day last 12 hours and six minutes on March 20.
Each year, equal lengths of day and night occur twice a year during the vernal and autumnal equinoxes, in March and September, respectively.
Following the vernal equinox, also known as an astronomical season, the country’s days become slightly longer and its nights become shorter.
The country does not have a spring season, but the weather is hot and dry from March to May.