Photosphere

The term photosphere is derived from Ancient Greek roots, φῶς, φωτός/phos, photos meaning "light" and σφαῖρα/sphaira meaning "sphere", in reference to it being a spherical surface that is perceived to emit light. == Sun's photosphere ==

: temperature and density. meaning human eyes perceive it as an overwhelmingly bright surface, and with a sufficiently strong neutral density filter, as a hueless, gray surface. It has a density of about 3 kg/m3; increasing with increasing depth. The Sun's photosphere is 100–400 kilometers thick. == Photospheric phenomena ==

In the Sun's photosphere, the most ubiquitous phenomenon are granules—convection cells of plasma each approximately in diameter with hot rising plasma in the center and cooler plasma falling in the spaces between them, flowing at velocities of . Each granule has a lifespan of only about twenty minutes, resulting in a continually shifting "boiling" pattern. Grouping the typical granules are supergranules up to in diameter with lifespans of up to 24 hours and flow speeds of about , carrying magnetic field bundles to the edges of the cells. Other magnetically related phenomena in the Sun's photosphere include sunspots and solar faculae dispersed between granules. These features are too fine to be directly observed on other stars; however, stellar spatial structures have been indirectly observed, and can behave like sunspots. We can refer to these as starspots, although clearly non-analogous features also may be present as well. == Notes ==