Editing Convection (section)

===Stellar physics===
{{main|Convection zone|granule (solar physics)}}
[[File:Structure of Stars (artist’s impression).jpg|thumb|right|300px|An illustration of the structure of the [[Sun]] and a [[red giant]] star, showing their convective zones. These are the granular zones in the outer layers of these stars.]]

The convection zone of a star is the range of radii in which energy is transported outward from the [[stellar core|core region]] primarily by convection rather than [[Radiation zone|radiation]]. This occurs at radii which are sufficiently [[Opacity (optics)|opaque]] that convection is more efficient than radiation at transporting energy.<ref>{{cite book
 | title=Discovering the Cosmos
 | first=Robert C. | last=Bless | year=1996
 | page=310 | isbn=9780935702675
 | publisher=University Science Books
 | url=https://books.google.com/books?id=jC47sk3mfjcC&pg=PA310 }}</ref>

Granules on the [[photosphere]] of the Sun are the visible tops of convection cells in the photosphere, caused by convection of [[plasma (physics)|plasma]] in the photosphere. The rising part of the granules is located in the center where the plasma is hotter. The outer edge of the granules is darker due to the cooler descending plasma. A typical granule has a diameter on the order of 1,000 kilometers and each lasts 8 to 20 minutes before dissipating. Below the photosphere is a layer of much larger "supergranules" up to 30,000 kilometers in diameter, with lifespans of up to 24 hours.
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