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  2. Kármán line - Wikipedia

    en.wikipedia.org/wiki/Kármán_line

    Earth's atmosphere photographed from the International Space Station.The orange and green line of airglow is at roughly the altitude of the Kármán line. [1]The Kármán line (or von Kármán line / v ɒ n ˈ k ɑːr m ɑː n /) [2] is a conventional definition of the edge of space; it is widely but not universally accepted.

  3. Scale height - Wikipedia

    en.wikipedia.org/wiki/Scale_height

    The earth atmosphere's ... with the equation for H given above to ... level value of ρ 0 roughly equal to 1.2 kg⋅m −3. At an altitude over 100 km, the atmosphere ...

  4. List of orbits - Wikipedia

    en.wikipedia.org/wiki/List_of_orbits

    In practice, only 1:1 ratio (geosynchronous) and 1:2 ratios (semi-synchronous) are common. Geosynchronous orbit (GSO): An orbit around the Earth with a period equal to one sidereal day, which is Earth's average rotational period of 23 hours, 56 minutes, 4.091 seconds. For a nearly circular orbit, this implies an altitude of approximately 35,786 ...

  5. Sub-orbital spaceflight - Wikipedia

    en.wikipedia.org/wiki/Sub-orbital_spaceflight

    An intercontinental ballistic missile is defined as a missile that can hit a target at least 5500 km away, and according to the above formula this requires an initial speed of 6.1 km/s. Increasing the speed to 7.9 km/s to attain any point on Earth requires a considerably larger missile because the amount of fuel needed goes up exponentially ...

  6. Valeriepieris circle - Wikipedia

    en.wikipedia.org/wiki/Valeriepieris_circle

    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 teacher named Ken Myers, whose username on the site gave the figure its name. [ 4 ]

  7. Geographical mile - Wikipedia

    en.wikipedia.org/wiki/Geographical_mile

    When each equatorial degree was divided into 18 leagues, the geographical mile was equal to ⁠ 1 / 54 ⁠ degree or about 2.06 kilometres (1.28 mi); when divided into 20 leagues, the geographical mile was equal to ⁠ 1 / 60 ⁠ degree, approximating the values provided above; and when divided into 25 leagues, the geographical mile was equal ...

  8. Outer space - Wikipedia

    en.wikipedia.org/wiki/Outer_space

    The altitude of 118 km (73.3 mi) above Earth was the midpoint for charged particles transitioning from the gentle winds of the Earth's atmosphere to the more extreme flows of outer space. The latter can reach velocities well over 268 m/s (880 ft/s).

  9. 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).