What phenomenon explains the variations in daylight length throughout the year?

• A. Earth’s rotation
• B. Earth’s orbit
• C. Earth's tilt on its axis
• D. Moon phases

Answer: (C)

The variation in daylight length throughout the year is primarily explained by Earth's tilt on its axis. The Earth is tilted at an angle of approximately 23.5 degrees relative to its orbital plane around the Sun. This axial tilt means that as the Earth orbits the Sun, different parts of the planet receive varying amounts of sunlight at different times of the year.

During summer in one hemisphere, that hemisphere is tilted toward the Sun, leading to longer days and shorter nights. Conversely, during winter, the same hemisphere is tilted away from the Sun, resulting in shorter days and longer nights. This axial tilt is the key factor in the changing length of daylight as the seasons progress.

In contrast, while Earth's rotation does cause the cycle of day and night, it does not account for the varying lengths of daylight throughout the year. Earth's orbit does influence its distance from the Sun but does not significantly affect daylight variations as the tilt does. Moon phases relate to the lunar cycle and do not impact the length of daylight at any given time.