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A diurnal cycle (or diel cycle) is any pattern that recurs every 24 hours as a result of one full rotation of the planet Earth around its axis. [1] Earth's rotation causes surface temperature fluctuations throughout the day and night, as well as weather changes throughout the year. The diurnal cycle depends mainly on incoming solar radiation. [2]
A circadian rhythm (/ s ər ˈ k eɪ d i ə n /), or circadian cycle, is a natural oscillation that repeats roughly every 24 hours.Circadian rhythms can refer to any process that originates within an organism (i.e., endogenous) and responds to the environment (is entrained by the environment).
In vertebrates, the master circadian clock is contained within the suprachiasmatic nucleus (SCN), a bilateral nerve cluster of about 20,000 neurons. [10] [11] The SCN itself is located in the hypothalamus, a small region of the brain situated directly above the optic chiasm, where it receives input from specialized photosensitive ganglion cells in the retina via the retinohypothalamic tract.
A lunar day is the time it takes for Earth's Moon to complete on its axis one synodic rotation, meaning with respect to the Sun. Informally, a lunar day and a lunar night is each approx. 14 Earth days. The formal lunar day is therefore the time of a full lunar day-night cycle.
Many types of animals are classified as being diurnal, meaning they are active during the day time and inactive or have periods of rest during the night time. [1] Commonly classified diurnal animals include mammals, birds, and reptiles. [2] [3] [4] Most primates are diurnal, including humans. [5]
The "Daily Show" live coverage with Jon Stewart airs at 11:00 p.m. ET/PT on Tuesday, Sept. 10, directly following the debate at 9 p.m. ET/PT. Presidential debate bingo: Play USA TODAY's free game ...
For those who haven't heard, Jon Stewart is back on The Daily Show every Monday, starting Feb. 12 and just in time for the heating up election cycle. Stewart was host of the show until 2015, when ...
A day is the time period of a full rotation of the Earth with respect to the Sun. On average, this is 24 hours (86,400 seconds). As a day passes at a given location it experiences morning, afternoon, evening, and night. This daily cycle drives circadian rhythms in many organisms, which are vital to many life processes.