Science & TechnologyGreek → English
Heliostat
/ˈhiːliəstæt/noun
A driven mirror that keeps a beam of sunlight aimed at a fixed point as the sun moves.
The Greek roots
ἥλιος
hḗlios
sun
στατός
statós
standing, made to stand
Literally: “sun made to stand still”
The story of the word
The mirror turns at half the rate the sun appears to move, which is what holds the reflected beam still, and the name says the rest: the sun made to stand. 's Gravesande described such a device in the 1740s and the term is credited to him. Solar telescopes use one to feed daylight down a fixed tube into a basement spectrograph, and power stations aim fields of them at a single tower of molten salt.
- How it travelled
- Ancient Greek → scientific coinage → English
- First recorded
- 18th century
Same family
heliumperihelionthermostatstatic
In a sentence
The heliostat lost tracking and the image drifted off the slit.
Ten thousand heliostats surround the tower, each one steered separately.