the.com/photosphere
The sun's visible skin, where light finally escapes after a 170,000-year traffic jam
means The photosphere is the glowing outer layer of the sun (or any star) from which light actually radiates into space — the surface we see, even though the star has no solid surface at all.
from Built from Greek 'photo-' (light) plus 'sphaira' (sphere/ball), the word simply means 'sphere of light.' Coined in the 1800s by astronomers who needed a precise term for the layer where a star stops being opaque and starts letting photons escape — the boundary between the blazing interior and the emptiness beyond.
- temperature
- about 5500 celsius, cooler than the layers above it
- depth
- only about 500 kilometers thick, remarkably thin
- origin of light
- photons spend millennia bouncing inside before reaching here
- etymology
- greek for light sphere, named by john herschel