From Greek 'astronomía' (star-arrangement), 'ástron' + 'nómos' (law) — sharing roots with 'star,' 'disaster,' 'economy,' and 'nomad.'
The branch of science that deals with celestial objects, space, and the physical universe as a whole.
From Greek 'astronomía' (ἀστρονομία), composed of 'ástron' (ἄστρον, star) + 'nómos' (νόμος, law, arrangement), from PIE *h₂ster- (star) + *nem- (to assign, to distribute). Literally 'the arrangement of the stars' or 'star-law.' The word distinguishes itself from 'astrología' (star-reasoning), though in antiquity the two were not sharply separated. The divergence between astronomy (science) and astrology
The words 'astronomy,' 'economy,' and 'nomad' all share the Greek root 'nómos/némein' (law/to distribute). Astronomy is 'star-arrangement,' economy is 'household-management' (oikos + nomos), and a nomad is one who 'distributes' or moves flocks to pasture. Meanwhile, 'disaster' means 'bad star' (dis- + astro), preserving the ancient belief that misfortune came from unfavorable stellar alignments.