Question

The star’s hour circle coincides with the observer meridian, the star is said to be:

• A. \(\text{Culminate} \)
• B. \(\text{Prime vertical crossing} \)
• C. \(\text{Elongation} \)
• D. \(\text{Nutation} \)

Hint:

A star reaches its highest point in the sky (upper culmination) or its lowest visible point (lower culmination) when it crosses the observer’s meridian.

Answer 1

The Correct Option is A

Step 1: Understanding the concept of culmination. A star culminates when it crosses the observer's meridian (the great circle passing through the celestial poles and the observer's zenith). This occurs twice a day—once at its upper culmination (highest altitude) and once at its lower culmination (lowest altitude below the horizon, not visible in many cases).
Step 2: Explanation of other terms. - Prime vertical crossing: When a celestial object crosses the prime vertical (the great circle perpendicular to the meridian). - Elongation: The angular distance of a celestial body from the Sun. - Nutation: A small periodic oscillation in the Earth's axial tilt due to gravitational interactions.
Step 3: Selecting the correct option. Since the question refers to the star's hour circle coinciding with the meridian, this defines culmination.