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  2. 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 ]

  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. 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.

  5. Sub-orbital spaceflight - Wikipedia

    en.wikipedia.org/wiki/Sub-orbital_spaceflight

    In this case the lowest required delta-v, to reach 100 km altitude, is about 1.4 km/s. Moving slower, with less free-fall, would require more delta-v. [citation needed] Compare this with orbital spaceflights: a low Earth orbit (LEO), with an altitude of about 300 km, needs a speed around 7.7 km/s, requiring a delta-v of about 9.2 km/s.

  6. Square degree - Wikipedia

    en.wikipedia.org/wiki/Square_degree

    Conversely, an average full moon (or the Sun) covers a 2 / 210 100 fraction, or less than 1/1000 of a percent (0.000 009 523 81) of the celestial hemisphere, or above-the-horizon sky. Assuming the Earth to be a sphere with a surface area of 510 million km 2, the area of Northern Ireland (14 130 km 2) represents a solid angle of 1.14 deg 2 ...

  7. Earth's circumference - Wikipedia

    en.wikipedia.org/wiki/Earth's_circumference

    Posidonius calculated the Earth's circumference by reference to the position of the star Canopus.As explained by Cleomedes, Posidonius observed Canopus on but never above the horizon at Rhodes, while at Alexandria he saw it ascend as far as 7 + 12 degrees above the horizon (the meridian arc between the latitude of the two locales is actually 5 degrees 14 minutes).

  8. 99% of humans are about to experience sunlight at the same time

    www.aol.com/weather/99-humans-experience...

    At 7:15 a.m. EDT on Saturday, July 8, around 99% of the Earth's population will see sunlight in the sky - as long as it isn't cloudy. ... (AP Photo/Michael Probst) It's time to break out the ...

  9. 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 ...