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  2. Earth - Wikipedia

    en.wikipedia.org/wiki/Earth

    As of September 2021, there are 4,550 operational, human-made satellites orbiting Earth. [193] There are also inoperative satellites, including Vanguard 1, the oldest satellite currently in orbit, and over 16,000 pieces of tracked space debris. [n 13] Earth's largest artificial satellite is the International Space Station (ISS). [194]

  3. List of Earth observation satellites - Wikipedia

    en.wikipedia.org/wiki/List_of_Earth_observation...

    Earth observation satellite missions developed by the ESA as of 2019. Earth observation satellites are Earth-orbiting spacecraft with sensors used to collect imagery and measurements of the surface of the earth. These satellites are used to monitor short-term weather, long-term climate change, natural disasters.

  4. Internal structure of Earth - Wikipedia

    en.wikipedia.org/wiki/Internal_structure_of_Earth

    Earth's outer core is a fluid layer about 2,260 km (1,400 mi) in height (i.e. distance from the highest point to the lowest point at the edge of the inner core) [36% of the Earth's radius, 15.6% of the volume] and composed of mostly iron and nickel that lies above Earth's solid inner core and below its mantle. [31]

  5. Communications satellite - Wikipedia

    en.wikipedia.org/wiki/Communications_satellite

    A medium Earth orbit is a satellite in orbit somewhere between 2,000 and 35,786 kilometres (1,243 and 22,236 mi) above the Earth's surface. MEO satellites are similar to LEO satellites in functionality. MEO satellites are visible for much longer periods of time than LEO satellites, usually between 2 and 8 hours.

  6. List of natural satellites - Wikipedia

    en.wikipedia.org/wiki/List_of_natural_satellites

    Of the Solar System's eight planets and its nine most likely dwarf planets, six planets and seven dwarf planets are known to be orbited by at least 300 natural satellites, or moons. At least 19 of them are large enough to be gravitationally rounded; of these, all are covered by a crust of ice except for Earth's Moon and Jupiter's Io. [1]

  7. Ionosphere - Wikipedia

    en.wikipedia.org/wiki/Ionosphere

    Relationship of the atmosphere and ionosphere. The ionosphere (/ aɪ ˈ ɒ n ə ˌ s f ɪər /) [1] [2] is the ionized part of the upper atmosphere of Earth, from about 48 km (30 mi) to 965 km (600 mi) above sea level, [3] a region that includes the thermosphere and parts of the mesosphere and exosphere.

  8. Satellite - Wikipedia

    en.wikipedia.org/wiki/Satellite

    The first artificial satellite launched into the Earth's orbit was the Soviet Union's Sputnik 1, on October 4, 1957. As of December 31, 2022, there are 6,718 operational satellites in the Earth's orbit, of which 4,529 belong to the United States (3,996 commercial), 590 belong to China, 174 belong to Russia, and 1,425 belong to other nations. [1]

  9. Exosphere - Wikipedia

    en.wikipedia.org/wiki/Exosphere

    The layers are to scale. From the Earth's surface to the top of the stratosphere (50km) is just under 1% of Earth's radius. The exosphere is a thin, atmosphere-like volume surrounding a planet or natural satellite where molecules are gravitationally bound to that body, but where the density is so low that the molecules are essentially collision ...