giác kính
Definition
- Noun:
- Apparent diameter: The angle, as seen by an observer, that the diameter of a distant object (especially a celestial body like the sun or moon) subtends at the point of observation. It is a measure of how large the object appears in the sky, not its physical size.
Usage Examples
- Noun:
- Giác kính của Mặt Trăng thay đổi tùy theo khoảng cách của nó đến Trái Đất. (The apparent diameter of the Moon changes depending on its distance from Earth.)
- Khi nhật thực toàn phần, giác kính của Mặt Trăng phải lớn hơn giác kính của Mặt Trời. (During a total solar eclipse, the apparent diameter of the Moon must be larger than the apparent diameter of the Sun.)
Advanced Usage
- This is a specialized term used primarily in astronomy and optics. In everyday conversation, it is more common to simply describe how large something "looks" or "appears."
Variants and Related Words
- Đường kính góc: (Noun) Angular diameter. This is a more modern or technical synonym for "giác kính."
- Góc nhìn: (Noun) Angle of view, field of view. Refers to the extent of the observable world seen through an optical instrument or the eye.
Synonyms
- Angular diameter: The angle subtended by the diameter of an object.
- Apparent size: A more general term for how large an object appears to be.
Related Scientific Concepts
- Parallax: The apparent shift in position of a nearby object against a distant background when viewed from different lines of sight.
- Arcsecond: A unit of angular measurement used in astronomy, equal to 1/3600 of a degree. Used to express very small apparent diameters.