Celestial Navigation · Navigational Triangle
The three vertices of the navigational (astronomical) triangle are the elevated pole, the zenith, and the body. What does the side from the zenith to the body represent?
- AThe local hour angle
- BThe polar distance (co-declination)
- CThe co-latitude
- DThe zenith distance (co-altitude, 90° − Ho)✓ Correct
Explanation
Zenith-to-body = zenith distance = 90° − altitude (co-altitude). Pole-to-zenith = co-latitude (90° − Lat); pole-to-body = polar distance (90° − dec). Sight reduction solves this spherical triangle for the computed altitude and azimuth.
Authority: Bowditch (Pub. No. 9), the navigational triangle
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