The equator has equal length of day and night throughout the year due to the Earth’s axial tilt and its rotation on its axis.
The Earth’s axis is not perpendicular to its orbital plane around the Sun but is instead inclined at an angle of about 23.5 degrees. This axial tilt is the reason for the change in seasons and the length of daylight throughout the year. However, the equator is an imaginary line around the middle of the Earth that is always perpendicular to the Earth’s axis.
Because of the Earth’s rotation, the equator receives direct sunlight all year round. As the Earth orbits the Sun, different parts of the equator receive varying amounts of sunlight, but the overall effect is that the length of day and night at the equator remains relatively constant. This is because the Sun’s path across the sky is almost directly overhead at the equator, so the length of daylight is almost equal to the length of nighttime.
During the equinoxes, which occur around March 20th and September 22nd, the Sun is directly over the equator, and the length of day and night is approximately equal all over the Earth. However, even outside the equinoxes, the length of day and night at the equator does not vary significantly throughout the year.
In summary, the equator has equal length of day and night throughout the year because it receives direct sunlight year-round, and its position relative to the Earth’s axis and orbital plane around the Sun allows for relatively consistent daylight hours.