Here's why:
* Equinox means equal: The word "equinox" comes from the Latin for "equal night." This means that on the equinox, both the day and night are approximately 12 hours long.
* Earth's tilt: The Earth's axis is tilted, which causes the seasons. The equinox is the time when the Earth's axis is neither tilted toward nor away from the sun. This means that the sun shines directly on the equator, resulting in roughly equal day and night hours for the entire planet.
Therefore, there are approximately 12 hours of daylight on the autumnal equinox in Los Angeles, just like everywhere else on Earth.