What is the complement of the altitude, measured from the zenith to the star along the vertical circle?

What is the complement of the altitude, measured from the zenith to the star along the vertical circle?

• A. Zenith Distance
• B. Azimuth
• C. Polar Distance
• D. Altitude

Answer: (A)

Altitude is the angle from the observer’s horizon up to the star. The complement measured from the zenith to the star along the same vertical circle is the zenith distance. Since the zenith is 90 degrees from the horizon, altitude and zenith distance add up to 90 degrees. So the zenith distance is the complement of the altitude. For example, if a star is 40° above the horizon, its zenith distance is 50°. The other terms describe different directions or reference points: azimuth is the compass direction along the horizon, polar distance is the angular distance from the celestial pole, and altitude is the angle above the horizon itself.

Altitude is the angle from the observer’s horizon up to the star. The complement measured from the zenith to the star along the same vertical circle is the zenith distance. Since the zenith is 90 degrees from the horizon, altitude and zenith distance add up to 90 degrees. So the zenith distance is the complement of the altitude. For example, if a star is 40° above the horizon, its zenith distance is 50°. The other terms describe different directions or reference points: azimuth is the compass direction along the horizon, polar distance is the angular distance from the celestial pole, and altitude is the angle above the horizon itself.