Old instruments
Artificial Horizon
Direct answer
Artificial Horizon is a reflective or optical device that supplies a horizontal reference when the natural horizon is unavailable.
Artificial Horizon is a level reference for altitude sights used in historical astronomy, timekeeping, or navigation.
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At a glance
- Found in
- Historical Almanacs & Instruments
- Related
- Filar Micrometer, Repeating Circle, Chronometer, Marine Chronometer
Artificial Horizon is a level reference for altitude sights used in historical astronomy, timekeeping, or navigation.
An engraved functional orientation; the page explains the real instrument, method, or publication.
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The story behind Artificial Horizon
Mercury troughs, glass reflectors, spirit levels, and bubble attachments have all served as artificial horizons.
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The Book of the Sky
How people learned to read the sky, from Babylon to the day you were born.
Why Artificial Horizon matters
Artificial Horizon matters because it makes land-based celestial altitude work possible away from a clear sea horizon.
How to read Artificial Horizon
Read Artificial Horizon by measuring the angle between the direct and reflected body and halving the doubled angle when the method requires.
Artificial Horizon in practice: an example
A sextant can observe the Sun and its reflection in a liquid horizon from an inland site.
Where readings of Artificial Horizon go wrong
Liquid horizons can be hazardous or disturbed by wind, and a doubled angle must not be mistaken for altitude.
Sources and editorial method
Research references used for this entry include:
- Royal Museums Greenwich: Astronomical and Navigational Instruments - Museum reference collection for historical observing, calculating, timekeeping, and navigation instruments.
- National Geospatial-Intelligence Agency: The American Practical Navigator - Official modern reference for navigation principles, celestial observations, sight reduction, and navigational tables.
- Source
- The Great Almanac Dictionary
- Category
- Historical Almanacs & Instruments
- Last updated
- 2026-09-26
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More in Historical Almanacs & Instruments
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Common questions
What is an artificial horizon?
Artificial Horizon is a reflective or optical device that supplies a horizontal reference when the natural horizon is unavailable.
What do people get wrong about an artificial horizon?
Liquid horizons can be hazardous or disturbed by wind, and a doubled angle must not be mistaken for altitude.
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