Earth & SkyGreek → English
Astrometry
/əˈstrɑmətri/noun
The branch of astronomy that measures the exact positions and motions of stars.
The Greek roots
ἄστρον
ástron
star
μέτρον
métron
measure
Literally: “star measuring”
The story of the word
The oldest practice in astronomy carries one of its newer names. Hipparchus was cataloguing stellar positions in the second century BC, but the word for what he was doing was assembled only in the nineteenth, once Bessel had pinned the parallax of 61 Cygni in 1838 and turned position-fixing into a distance measure. The European Gaia mission does the same job to microarcsecond precision.
- How it travelled
- Ancient Greek → scientific coinage → English
- First recorded
- 19th century
Same family
astronomygeometryasteriskdisaster
In a sentence
Astrometry gave us the first honest measurement of how far away a star is.
Her thesis used astrometry to hunt for the wobble of an unseen companion.