sextant
2 synonyms for sextant, grouped by meaning and by how common each one is.
Noun — A navigational instrument with a graduated arc and mirrors, used to measure the angle between a celestial body and the horizon in order to work out latitude and position at sea.
Synonyms
Less common
Still standard English, but they carry more weight.
Rare, literary or technical
Precise, but they will stand out — check the sense before using one.
How to use sextant
The word patterns that sound natural to a native speaker.
take a sight with a sextant
a marine sextant
sextant altitude
shoot the sun
Neutral; nautical and historical contexts.
Etymology
From Latin sextans 'a sixth part', because the instrument's graduated arc spans a sixth of a circle, that is sixty degrees.
Full origin of sextant →Frequently asked questions
How does a sextant work?
You look at the horizon through a half-silvered mirror and swing an arm carrying a second mirror until the reflected image of the sun or a star sits exactly on that horizon line. The angle read off the arc, combined with the exact time and published tables, gives your position.
What is the difference between a sextant and an astrolabe?
An astrolabe is an older instrument, held hanging vertically, that measures a body's altitude against a fixed scale and is hard to use on a moving deck. A sextant uses mirrors to bring the body and the horizon into the same view, so it stays accurate on a pitching ship and is far more precise.
Are sextants still used?
Yes, though rarely as the primary method. Merchant and naval officers still train in celestial navigation as a backup for GPS failure or jamming, and ocean sailors carry a sextant for the same reason.
