Where is Polaris (the Pole Star) below the horizon? At which latitude(s) would Polaris remain below the horizon for a terrestrial observer?

Introduction / Context:
Polaris lies near the north celestial pole. Its altitude above the horizon closely equals the observer’s latitude in the northern hemisphere. Understanding where it lies relative to the horizon is useful for navigation and astronomical orientation.

Given Data / Assumptions:

• Altitude of Polaris ≈ observer’s latitude φ (north positive).
• At the equator (φ = 0°) Polaris is on the horizon.
• In the southern hemisphere (φ < 0°), Polaris is below the horizon by |φ| degrees.

Concept / Approach:
If φ is negative (south latitude), the north celestial pole is below the horizon. Therefore, any south latitude places Polaris below the horizon. The deeper south you go, the lower it is below the horizon.

Step-by-Step Solution:
Check each option:10° N: Polaris altitude ≈ 10° above horizon → visible.50° N: altitude ≈ 50° → clearly visible.Equator 0°: Polaris lies on the horizon → neither above nor below.5° S: Polaris ≈ 5° below horizon → not visible → correct choice.15° N: Polaris ≈ 15° above horizon → visible.

Verification / Alternative check:
This simple rule is widely used in field navigation: Polaris altitude approximately equals the observer’s latitude (north positive).

Why Other Options Are Wrong:
Options at north latitudes place Polaris above the horizon; at the equator it is on, not below, the horizon.

Common Pitfalls:
Assuming visibility at the equator; refraction and terrain can make it difficult, but geometrically its altitude is ~0° at 0° latitude.

Final Answer:
5° S latitude