地ち心しん天てん頂ちょう

noun

geocentric zenith

Technical term in astronomy and geodesy; the point on the celestial sphere directly above the observer, defined relative to the Earth's center rather than the local vertical.

• 地ち心しん天てん頂ちょうは、観かん測そく者しゃの位い置ちにおける地ち球きゅうの中ちゅう心しんから天てん球きゅうに引ひいた線せんの方ほう向こうにあります。

  The geocentric zenith is in the direction of a line drawn from the Earth's center at the observer's location to the celestial sphere.