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  2. Earth radius - Wikipedia

    en.wikipedia.org/wiki/Earth_radius

    Earth radius (denoted as R 🜨 or R E) is the distance from the center of Earth to a point on or near its surface. Approximating the figure of Earth by an Earth spheroid (an oblate ellipsoid), the radius ranges from a maximum (equatorial radius, denoted a) of nearly 6,378 km (3,963 mi) to a minimum (polar radius, denoted b) of nearly 6,357 km (3,950 mi).

  3. Timeline of wars - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_wars

    The timeline of wars has been split up in the following periods: List of wars: before 1000. List of wars: 1000–1499. List of wars: 1500–1799. List of wars: 1800–1899. List of wars: 1900–1944. List of wars: 1945–1989. List of wars: 1990–2002.

  4. Military Grid Reference System - Wikipedia

    en.wikipedia.org/wiki/Military_Grid_Reference_System

    An MGRS grid reference is a point reference system. When the term 'grid square' is used, it can refer to a square with a side length of 10 km (6 mi), 1 km, 100 m (328 ft), 10 m or 1 m, depending on the precision of the coordinates provided. (In some cases, squares adjacent to a Grid Zone Junction (GZJ) are clipped, so polygon is a better ...

  5. History of the metre - Wikipedia

    en.wikipedia.org/wiki/History_of_the_metre

    History of the metre. An early definition of the metre was one ten-millionth of the Earth quadrant, the distance from the North Pole to the Equator, measured along a meridian through Paris. The history of the metre starts with the Scientific Revolution that is considered to have begun with Nicolaus Copernicus 's publication of De revolutionibus ...

  6. Geologic time scale - Wikipedia

    en.wikipedia.org/wiki/Geologic_time_scale

    Principles. The geologic time scale is a way of representing deep time based on events that have occurred throughout Earth's history, a time span of about 4.54 ± 0.05 Ga (4.54 billion years). [5] It chronologically organises strata, and subsequently time, by observing fundamental changes in stratigraphy that correspond to major geological or ...

  7. Adams Synchronological Chart or Map of History - Wikipedia

    en.wikipedia.org/wiki/Adams_Synchronological...

    18434872. Adams Synchronological Chart or Map of History, originally published as Chronological Chart of Ancient, Modern and Biblical History is a wallchart that graphically depicts a Biblical genealogy alongside a timeline composed of historic sources from the history of humanity from 4004 BC to modern times.

  8. History of Earth - Wikipedia

    en.wikipedia.org/wiki/History_of_Earth

    The first eon in Earth's history, the Hadean, begins with the Earth's formation and is followed by the Archean eon at 3.8 Ga. [2]: 145 The oldest rocks found on Earth date to about 4.0 Ga, and the oldest detrital zircon crystals in rocks to about 4.4 Ga, [34] [35] [36] soon after the formation of the Earth's crust and the Earth itself.

  9. Eratosthenes - Wikipedia

    en.wikipedia.org/wiki/Eratosthenes

    With a stade of 185 m (607 ft), 804,000,000 stadia is 149,000,000 km (93,000,000 mi), approximately the distance from the Earth to the Sun. Eratosthenes also calculated the Sun's diameter. According to Macrobius, Eratosthenes made the diameter of the Sun to be about 27 times that of the Earth. [17] The actual figure is approximately 109 times. [26]