apparent horizon
Học thuậtThân thiện
Definition
Noun: - The line at which the sky and Earth appear to meet: The apparent horizon is the visible boundary line between the earth (or sea) and the sky, as seen by an observer. It is the circle where distant objects seem to disappear from view due to the curvature of the Earth.
Usage
The term "apparent horizon" is used in contexts such as navigation, astronomy, and general observation to describe the visible limit of one's field of view where the sky meets the land or water. - From the ship's deck, the sailor watched the sun dip below the apparent horizon. - The pilot knew that the city would become visible once they flew above the apparent horizon.
Advanced Usage
- In astronomy and physics, the term can be distinguished from the "true" or "astronomical" horizon, which is a calculated plane. The apparent horizon is the one directly perceived by an observer.
- For celestial navigation, corrections must be made for the difference between the apparent horizon and the true horizon.
Variants and Related Words
- Horizon (n): A more common term for the apparent horizon, often used interchangeably in everyday language.
- The mountains were a dark silhouette on the horizon.
- Skyline (n): Often refers to the outline of land or buildings against the sky, which can form part of the apparent horizon in urban settings.
- The famous skyline of the city appeared on the horizon.
Synonyms
- Visible horizon: Emphasizes the aspect of being seen.
- Sensible horizon: An older term with a similar meaning, focusing on perception.
Related Phrases
- Below the horizon: Refers to an object or celestial body that is not visible because it is beyond the apparent horizon.
- The constellation is below the horizon at this time of year.
- On the horizon: Often used figuratively to mean something is imminent or becoming visible in the future.
- New technological advances are on the horizon.
Noun
- the line at which the sky and Earth appear to meet