Category: Hours

In fact, most places on earth have more hours of day than night on those two days of the year, due to the earth’s atmosphere and our definition of sunrise and sunset. One of the reasons most places on earth do not have exactly 12 hours of light and 12 hours of darkness on the equinox is the definition of sunrise and sunset. If sunrise and sunset were defined as the time when the geometrical center of the sun passes the horizon, day and night would be exactly 12 hours long. Although day and night are not exactly the same length on the day of the equinox, there are days when the hours of sunrise and night are very close. Equinox means “equal night” in Latin, which means the day and night at the equinox are exactly 12 hours long. Another reason day is longer than 12 hours on the equinox is that the Earth atmosphere refracts sunlight. This refraction, or bending, of light causes the top of the sun to be visible from Earth for a few minutes before the edge reaches the horizon. Sunrise and sunset are defined as the exact time when the apex of the solar disk touches the eastern and western horizons, respectively. As a result, each day on Earth, including the equinoxes, is at least six minutes longer than it would be without this refraction. Even in Longyearbyen, one of the northernmost cities in the world, the day lasts 12 hours and 37 minutes. To the south, in Melbourne, Australia, the day will last 12 hours and 6 minutes. In Amsterdam, the day will last 4 minutes at 12 hours and 12 minutes. Only the September equinox and the March equinox have nearly the same length of day and night. Residents of Johannesburg also enjoy the same number of daylight hours. Because of the time it takes for the sun to fully set, which can take several minutes, the day is slightly longer than the night on the equinox. This day is called the equinox and its length depends on the latitude of the place and may occur several days or weeks before or after the equinox.