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Systematically observing the sunrise, people discovered that it occurs between two extreme locations at the horizon and eventually noted the midpoint between the two. Later it was realized that this happens on a day when the duration of the day and the night are practically equal and the word "equinox" comes from Latin aequus, meaning "equal", and nox, meaning "night".
In its apparent motion on the day of an equinox, the Sun's disk crosses the Earth's horizon directly to the east at sunrise; and again, some 12 hours later, directly to the west at sunset. The March equinox, like all equinoxes, is characterized by having an almost exactly equal amount of daylight and night across most latitudes on Earth. [14]
Earth Day is an annual event on April 22 to demonstrate support for environmental protection.First held on April 22, 1970, it now includes a wide range of events coordinated globally by EARTHDAY.ORG (formerly Earth Day Network) [1] including 1 billion people in more than 193 countries.
Dive into Earth Day's rich history and global influence. Uncover its origins and ongoing relevance in shaping environmental consciousness. Everything to know about the history of Earth Day
Known affectionately to scientists as the "boring billion," there was a seemingly endless period in the world's history when the length of a day stayed put. The time when a day on Earth was just ...
A 24-hour day contained twelve Dannas, [11] which in turn, taking into account the Babylonian model of the mean sun [clarification needed], comprised twelve equinoctial units, each lasting 120 minutes [12] The equivalent hours had the Sumerian System of the distance covered on foot in broad daylight as a basis. The unit of measurement, which ...
The length of the day (LOD), which has increased over the long term of Earth's history due to tidal effects, is also subject to fluctuations on a shorter scale of time. Exact measurements of time by atomic clocks and satellite laser ranging have revealed that the LOD is subject to a number of different changes.
For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the Solar System as Earth's North Pole. [1] Due to Earth's axial tilt of 23.439281°, there is a seasonal variation in the lengths of the day and night. There is also a seasonal variation in temperatures, which ...