Final answer:
The exact day length in Manila on February 25th, the People Power Anniversary, varies slightly each year and must be checked with an astronomical almanac. The day is slightly longer than 12 hours on the vernal equinox due to atmospheric refraction. The Gregorian calendar has a discrepancy of about one day every 3300 years.
Step-by-step explanation:
The question pertains to the day length in Manila on the People Power Anniversary, which is February 25th and 55 days after January 1st. However, precise day length can vary slightly from year to year due to the elliptical shape of Earth's orbit and the tilt of its axis. To find out the exact day length for Manila on February 25th, one would typically consult an astronomical almanac or use specific software that provides this data.
Regarding the related information provided on equinoxes and the day length on Earth, it is noted that on the day of the vernal equinox, the day length for all places on Earth is slightly longer than 12 hours due to atmospheric refraction bending the sunlight above the horizon earlier at sunrise and later at sunset. This causes the day to appear longer than the night, even though, theoretically, both should be equal.
For the Gregorian calendar accuracy, approximately every 3300 years, a single day discrepancy accumulates because the actual solar year is slightly less than 365.25 days. Calendar adjustments, similar to the leap year concept, are proposed to address this issue over long periods.