Day & Night Solar
Wiki, Facts

 Day & Night Solar facts

• In common usage, it is either an interval equal to 24 hours or daytime, the consecutive period of time during which the Sun is above the horizon
• The period of time during which the Earth completes one rotation with respect to the Sun is called a solar day
• Several definitions of this universal human concept are used according to context, need and convenience
• In 1960, the second was redefined in terms of the orbital motion of the Earth, and was designated the SI base unit of time
• The unit of measurement "day", redefined in 1960 as 86 400 SI seconds and symbolized d, is not an SI unit, but is accepted for use with SI
• A civil day is usually 86 400 seconds, plus or minus a possible leap second in Coordinated Universal Time (UTC), and occasionally plus or minus an hour in those locations that change from or to daylight saving time
• The word day may also refer to a day of the week or to a calendar date, as in answer to the question "On which day?" The life patterns of humans and many other species are related to Earth's solar day and the day-night cycle (see circadian rhythms)
• In recent decades the average length of a solar day on Earth has been about 86 400
• 002 seconds (24
• 000 000 6 hours) and there are about 365