ATLAS

Official versionOMEGA-3-21-4Sheet 4 of 5 of the dossier Celestial dome

What science and space agencies say about the sky

The atmosphere, the blue sky, twinkling stars and the spacecraft that left Earth without meeting a dome.

Photograph of the whole sunlit Earth showing Africa and Antarctica, with no dome or edge.
The Blue Marble: full view of the Earth photographed by the Apollo 17 crew on 7 December 1972, on the way to the Moon, from about 29,400 km. NASA/Apollo 17 crew; taken by either Harrison Schmitt or Ron Evans · public domain · Wikimedia Commons

Summary

This sheet gathers what the sciences and space agencies say about the sky, point by point against the dome thesis. The atmosphere has no sharp edge: its density falls off exponentially with altitude and it fades into space, and the Kármán line at 100 kilometres is a convention with no distinct physical significance. A fact-check citing NASA material notes that the outermost layer, the exosphere, does not end abruptly with an impenetrable shell but fades into space over thousands of miles. The blue of the sky comes from the scattering of sunlight by air molecules, and stars twinkle because their light crosses the atmosphere; seen from the Moon, where there is none, they do not twinkle at all. On the other side of the sky, Voyager 1 officially became the first human-made object to enter interstellar space, announced in 2013, and the retroreflector left on the Moon by the Apollo 11 astronauts in 1969 still lets laser pulses measure the Earth-Moon distance to a few centimetres. Asked directly about the dome claim, a NASA Goddard communications manager told Reuters that the agency has sent spacecraft far into the solar system and beyond without encountering a dome. These are the positions of institutions and of the scientific literature; they are consistent with each other, and none of them leaves room for a solid vault. What remains open are questions of definition, such as where space is said to begin, not the existence of a barrier.

Official version

  1. Official version

    Earth's atmosphere has no sharp edge: its density decreases exponentially with altitude and it fades into space.

  2. Official version

    The Kármán line, at 100 km, is a conventional definition of the edge of space with no distinct physical significance; experts disagree on where the atmosphere ends.

    • Kármán line, Wikipedia
      there is a rather gradual difference between the characteristics of the atmosphere at the line, and experts disagree on defining a distinct boundary where the atmosphere ends and space begins.
  3. Official version

    The sky is blue because air molecules scatter blue light more than red light (Rayleigh scattering), not because of a coloured vault.

    • Why is the sky blue?, Royal Museums Greenwich (Royal Observatory)
      Therefore, blue light is scattered more than red light and the sky appears blue during the day.
  4. Official version

    Stars twinkle because their light crosses the atmosphere; seen from the Moon, where there is no atmosphere, they do not twinkle at all.

  5. Official version

    NASA's Voyager 1 is officially the first human-made object to venture into interstellar space, announced in September 2013.

    • NASA’s Voyager 1 Reaches Interstellar Space, Johns Hopkins University Applied Physics Laboratory (NASA release), 12 September 2013
      NASA’s Voyager 1 spacecraft officially is the first human-made object to venture into interstellar space.
  6. Official version

    The Apollo 11 astronauts placed the first laser retroreflector on the Moon in 1969; laser pulses bounced off it give the Earth-Moon distance to about 3 centimetres.

    • Measuring the Moon's Distance, NASA Goddard Space Flight Center (eclipse.gsfc.nasa.gov)
      The first laser ranging retroreflector was positioned on the Moon in 1969 by the Apollo 11 astronauts.
  7. Official version

    Asked about the dome claim, a NASA Goddard communications manager said that NASA has sent spacecraft far into the solar system and beyond and has not encountered a dome; more than 250 robotic spacecraft have flown since 1958.

  8. Official version

    The outermost layer of the atmosphere, the exosphere, does not end abruptly with an impenetrable shell but gradually fades into outer space over thousands of miles.

Play on YouTube (third-party content)
NASA JPL video explaining how the team found that Voyager 1 had reached interstellar space (2013).
NASA Jet Propulsion Laboratory
Play on YouTube (third-party content)
NASA Space Place explains why the sky is blue.
NASA Space Place