Day

A day is a unit of time. In common usage, it is an interval equal to 24 hours. It also can mean the consecutive period of time during which the Sun is above the horizon, also known as daytime. 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 1967, the second was redefined in terms of the wavelength of light, and was designated the SI base unit of time. The unit of measurement "day", redefined in 1967 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 also 86 400 seconds, plus or minus a possible leap second in Coordinated Universal Time (UTC), and, in some locations, occasionally plus or minus an hour when changing 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).

2012 Formula One season

The 2012 Formula One season was the 63rd season of FIA Formula One motor racing. It featured the 2012 FIA Formula One World Championship, a motor racing series for Formula One cars, recognised by the Fédération Internationale de l'Automobile (FIA) — the governing body of motorsport — as the highest class of competition for open-wheel racing cars. The championship was contested over twenty rounds, which started in Australia on 18 March and ended in Brazil on 25 November. The 2012 season saw the return of the United States Grand Prix, which was held at the Circuit of the Americas, a purpose-built circuit in Austin, Texas. After being cancelled in 2011 due to civil protests, the Bahrain Grand Prix also returned to the calendar.