Earth & SkyGreek → English
Photosphere
/ˈfoʊtəsfɪər/noun
The visible glowing surface of the sun or another star.
The Greek roots
φῶς
phôs
light
σφαῖρα
sphaîra
ball, globe
Literally: “light sphere”
The story of the word
John Herschel needed a name for the shining shell of the sun and bolted φῶς onto σφαῖρα in the 1840s. It is a surface only in the optical sense. Nothing solid is there; the gas has simply thinned enough at that depth to let light escape, so the sun appears to have an edge.
- How it travelled
- Ancient Greek → scientific coinage → English
- First recorded
- 1840s
Same family
photographphotonatmospherehemisphere
In a sentence
Sunspots are cooler patches in the photosphere, dark only by comparison.