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The orbital speed of Earth averages about 29.78 km/s (107,200 km/h; 66,600 mph), which is fast enough to travel a distance equal to Earth's diameter, about 12,742 km (7,918 mi), in seven minutes, and the distance from Earth to the Moon, 384,400 km (238,900 mi), in about 3.5 hours.
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).
It calculates the Earth's diameter to be 8,000 miles (modern: 7,928 miles), [6] ... The Surya Siddhanta is a text on astronomy and time keeping, ...
It is usually quoted as "light-time for unit distance" in tables of astronomical constants, and its currently accepted value is 499.004 786 385(20) s. [3] [4] The mean diameter of Earth is about 0.0425 light-seconds. The average distance between Earth and the Moon (the lunar distance) is about 1.282 light-seconds.
The geographical mile is an international unit of length determined by 1 minute of arc ( 1 / 60 degree) along the Earth's equator. For the international ellipsoid 1924 this equalled 1855.4 metres. [1] The American Practical Navigator 2017 defines the geographical mile as 6,087.08 feet (1,855.342 m). [2]
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).
[38] [39] He then measured the apparent sizes of the Sun and the Moon and concluded that the apparent diameter of the Sun was equal to the apparent diameter of the Moon at the Moon's greatest distance, and from records of lunar eclipses, he estimated this apparent diameter, as well as the apparent diameter of the shadow cone of Earth traversed ...
A nautical mile is a unit of length used in air, marine, and space navigation, and for the definition of territorial waters. [2] [3] [4] Historically, it was defined as the meridian arc length corresponding to one minute ( 1 / 60 of a degree) of latitude at the equator, so that Earth's polar circumference is very near to 21,600 nautical miles (that is 60 minutes × 360 degrees).