Question

The angle between the direction of star and the direction of earth's axis of rotation is called as

• A. Co-declination
• B. Co-latitude
• C. Declination
• D. Latitude

Hint:

In celestial navigation and astronomy, 'co-' prefix often implies the complement to 90 degrees. So, Co-declination is \( 90^\circ - \text{Declination \), representing the angular distance from the celestial pole. Similarly, Co-latitude is \( 90^\circ - \text{Latitude \), representing the angular distance from the observer's zenith to the celestial equator or from the observer's geographical pole to the observer's zenith.

Answer 1

The Correct Option is A

In the context of celestial observations, the terms used to describe the angles between celestial objects and Earth's reference axes are specific. Here, we are interested in identifying the term that describes the angle between the direction of a star and the direction of Earth's axis of rotation.

The options given are:

• Co-declination
• Co-latitude
• Declination
• Latitude

Let's analyze each:

• Declination: This is the angle between the celestial equator and the line extending from the Earth to the star. It is analogous to latitude on Earth's surface but projected onto the celestial sphere.
• Latitude: This represents the angle between a point on Earth's surface and the equatorial plane. It does not address celestial objects outside of Earth.
• Co-latitude: This is the complementary angle of latitude, i.e., 90° minus the given latitude. It relates to Earth's surface, not directly to celestial observations.
• Co-declination: The complementary angle of declination, calculated as 90° minus the declination, gives us the angle between the direction to the star and Earth's rotational axis.

Based on this explanation, the correct answer is Co-declination, as it specifically represents the angle between the direction of a star and Earth's axis of rotation.