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Currently most of the objects of mass between 10 9 kg to 10 12 kg (less than 1000 teragrams (Tg)) listed here are near-Earth asteroids (NEAs). The Aten asteroid 1994 WR12 has less mass than the Great Pyramid of Giza, 5.9 × 10 9 kg. For more about very small objects in the Solar System, see meteoroid, micrometeoroid, cosmic dust, and ...
The ellipsoid WGS-84, widely used for mapping and satellite navigation has f close to 1/300 (more precisely, 1/298.257223563, by definition), corresponding to a difference of the major and minor semi-axes of approximately 21 km (13 miles) (more precisely, 21.3846857548205 km). For comparison, Earth's Moon is even less elliptical, with a ...
Kepler-452b (sometimes quoted to be an Earth 2.0 or Earth's Cousin [3] [4] based on its characteristics; also known by its Kepler Object of Interest designation KOI-7016.01) is a super-Earth exoplanet orbiting within the inner edge of the habitable zone of the sun-like star Kepler-452 and is the only planet in the system discovered by the Kepler space telescope.
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).
Proxima Centauri b is the closest exoplanet to Earth, [20] at a distance of about 4.2 ly (1.3 parsecs). [5] It orbits Proxima Centauri every 11.186 Earth days at a distance of about 0.049 AU, [1] over 20 times closer to Proxima Centauri than Earth is to the Sun. [21] As of 2021, it is unclear whether it has an eccentricity [e] [24] but Proxima Centauri b is unlikely to have any obliquity. [25]
A size estimate for Proxima Centauri was obtained by the Canadian astronomer John Stanley Plaskett in 1925 using interferometry. The result was 207,000 miles (333,000 km), or approximately 0.24 R ☉. [99] In 1951, American astronomer Harlow Shapley announced that Proxima Centauri is a flare star. Examination of past photographic records showed ...
Valeriepieris circle. The original 2013 map by Ken Myers, with the interior of the circle inverted. A Valeriepieris circle[ 1][ 2][ 3] is a figure drawn on the Earth's surface such that the majority of the human population lives within its interior. The concept was originally popularized by a map posted on Reddit in 2013, made by a Texas ESL ...
This table shows all cities or conurbations with a total urbanised area of at least 5,000 km 2, according to Demographia 's annual World Urban Areas [57] publication, that uses a consistent methodology between countries to provide comparable population and area figures. Urban area. Country. Built-up land area.