![]() ![]() Within this layer also occur the sunspots, the most visible of photospheric features. This supergranulation indicates the existence of larger convective regions. Larger areas of the photosphere may appear slightly brighter (warmer) or fainter (cooler) than other regions. Photons, however, endure enormous numbers of collisions with nuclei and electrons and may take tens of thousands of years to work their way into the outer regions of the Sun. Convection is far more efficient at moving energy, with energy passing outward through the solar convective zone (the outer 15% of the Sun) in a matter of hours. In the deeper interior, photons are able to move energy outward by slow diffusion in a radiative zone. ![]() This is direct observational evidence that the photosphere is also the top of a convective zone in the Sun (like the mass motion in a pot of boiling water that carries heat from the bottom to the top of the water). Meanwhile, the surrounding cooler and darker regions are sinking back into the solar interior. These regions last only a few minutes before they dissipate and are replaced with other rising masses of warmer gas. The brighter regions are about 100 K hotter than surrounding regions and are rising at 2–3 km/s. It has a mottled or granular appearance, granulation, due to small regions of warmer and cooler material. Moving outward from the core of the Sun, the density, temperature, and gas pressure all decrease until, in a thin layer (only 400 kilometers thick), the material gradually changes from being completely opaque (light cannot pass through it) to being completely transparent.Ĭlose inspection of the photosphere shows that it is not a uniformly bright layer, but has variations. The photosphere is the visible “surface” of the Sun, but is not a true or solid surface because the Sun is completely gaseous. SETI-The Search for Extraterrestrial Intelligence.Internal Structure Standard Solar Model.Interior Structure: Core, Mantle, Crust.Minor Objects: Asteroids, Comets, and More.Origin and Evolution of the Solar System. ![]()
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