What is the angular distance measured along the vertical circle from the horizon to a celestial body?

• A. Azimuth
• B. Zenith Distance
• C. Altitude
• D. Right Ascension

Answer: (C)

Altitude is the angular distance above the local horizon, measured along the vertical circle that passes through the celestial body and the zenith. It tells you how high the object is in the sky: 0° means it lies on the horizon, 90° means it’s directly overhead at the zenith. The complement of altitude is the zenith distance (90° minus altitude), which is the angle from the zenith down to the object. Azimuth is the horizontal direction around the horizon (where along the horizon the object is), and right ascension is a coordinate along the celestial equator, not an angle from the horizon.