| 单词 | zenith line |
| 释义 | > as lemmaszenith line zenith line n. now rare (a) an arc from the zenith to the horizon, which it intersects at right angles (= azimuth n. 1), esp. to the point due east on the horizon; (b) a straight vertical line between the zenith point at a given location and the centre of the earth. ΘΚΠ the world > the universe > celestial sphere > circle of celestial sphere > [noun] > great circle > azimuth circle azimuthc1400 vertical circle1559 zenith line1585 vertical1669 1585 J. Blagrave Math. Iewel 39 The 15. azimuth reckoned from the East or zenith line. a1652 S. Foster Elliptical Horologiography (1654) 69 (heading) How to draw and divide the Ellipsis upon any Plain, to an Index that stands upright..to the Zenith line of the place, or perpendicular to the plain of the Horizon. 1778 N. D. Falck Ready Observator (ed. 2) 80 The imaginary Lines then, perpendicular to the Zenith Line from the different Elevations..are to be understood as the respective true Horizons. 1871 Exchange & Mart 19 Apr. 480/1 The white streamers [of the aurora] extended almost to the eastern horizon, and some were to the south of the zenith line. 1987 J. Raban in Granta No. 10. 29 Your latitude is the angle formed at the Earth's centre between the equator and your zenith-line. < as lemmas |
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