The Sun · Stars
Photosphere
Say it: FOH-tuh-sfeer IPA: /ˈfoʊtəsfɪr/ noun
Photosphere: The visible surface of the Sun or another star, the layer from which most of its light escapes.
The Sun is gas all the way through, so it has no solid surface. The photosphere is the depth at which the gas becomes transparent enough for light to stream out into space.
- Example
- Sunspots appear darker than the surrounding photosphere.
- Why astronomers use it
- Almost everything we learn from sunlight comes from this layer.
- Tiny cosmic connection
- The photosphere is cooler than the chromosphere and corona above it, a puzzle solar physicists still study.
Observatory The Sun Stars
Where to check it
Written for Cool Moon Facts in its own words; the sources cover the same idea in more depth.