What is the name of the point of intersection of the great circle passing through the celestial north pole P and the Zenith Z, with the celestial equator? (Point T in the figure)

In Italian this point is called "Mezzocielo" (English machine translation), which translates into mid-sky, since it is located halfway between the Zenith and the horizon for an observer in Italy ($\phi \approx 40^{\circ}$). Point B in the figure

  • 2
    $\begingroup$ I don't believe that that point has a specific name in English. $\endgroup$
    – James K
    Mar 30, 2020 at 20:59
  • $\begingroup$ It actually is quite an important point, since the Hour Angle (HA) is measured from it. Shouldn't we give it a name :)? $\endgroup$ Mar 31, 2020 at 15:29
  • $\begingroup$ "Should" is a different question. $\endgroup$
    – James K
    Mar 31, 2020 at 15:39
  • $\begingroup$ The hour angle is really a measure of the angle between the plane of the meridian and the plane passing through the object, so it does not need to be measured along the equator. Like James K, I do not know of a single work to describe point T. The closest would be "equator culmination". $\endgroup$
    – JohnHoltz
    Mar 31, 2020 at 16:06
  • 1
    $\begingroup$ There's a related point called the midheaven (abbreviated as MC from Latin Medium Coeli), which is the intersection of the meridian with the ecliptic (not the celestial equator). $\endgroup$
    – PM 2Ring
    Dec 28, 2020 at 13:51

1 Answer 1


I've checked several sources. Where this term appears in dictionaries, it is translated with a definition, and not a gloss (usually if a direct translation exists in English only a gloss is given) For example https://en.wiktionary.org/wiki/mezzocielo intersection of the meridian of a given place with the celestial equator.

I conclude that English speaking astronomers have not had the benefit of single word translation of mezzocielo.


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