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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).
They arrived at a figure for the solar parallax of 9.5 arcseconds, [Note 1] equivalent to an Earth–Sun distance of about 22,000 Earth radii. [ Note 2 ] They were also the first astronomers to have access to an accurate and reliable value for the radius of Earth , which had been measured by their colleague Jean Picard in 1669 as 3,269,000 toises .
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]
t. e. Earth's circumference is the distance around Earth. Measured around the equator, it is 40,075.017 km (24,901.461 mi). Measured passing through the poles, the circumference is 40,007.863 km (24,859.734 mi). [1] Measurement of Earth's circumference has been important to navigation since ancient times. The first known scientific measurement ...
Typical nuclear weapon yields used during Cold War planning for EMP attacks were in the range of 1 to 10 Mt (4.2 to 41.8 PJ). [35]: 39 This is roughly 50 to 500 times the size of the Hiroshima and Nagasaki bombs. Physicists have testified at United States Congressional hearings that weapons with yields of 10 kt (42 TJ) or less can produce a ...
One well-known difference is the placement of the center of the Earth, with the two systems differing by about 2.2 metres (7.2 ft). [14] In addition, NAD 83 is defined to remain constant over time for points on the North American Plate, whereas WGS 84 is defined with respect to the average of stations all over the world. Thus the two systems ...
It used the International Ellipsoid of 1924 ("Hayford-Ellipsoid" of 1909) (radius of the Earth's equator 6378.388 km, flattening 1/297, both exact). That spheroid was an early attempt to model the whole Earth and was widely used around the world until the 1980s when GRS 80 and WGS 84 were established.
The Schwarzschild radius or the gravitational radius is a physical parameter in the Schwarzschild solution to Einstein's field equations that corresponds to the radius defining the event horizon of a Schwarzschild black hole. It is a characteristic radius associated with any quantity of mass. The Schwarzschild radius was named after the German ...