Tuesday, 18 August 2015

star - Does the sun have a feature like the red spot on Jupiter?

The Sun has lots of features "like the red spot", but they are dissimilar too.



Similarities: The Sun's photosphere - the bit we can see - is entirely gaseous; the photosphere rotates differentially with solar latitude; the gas is turbulent. There are features that can be seen quite easily - these are the dark magnetic sunspots, typically of size a few thousand km; and the pattern of bright points surrounded by dark lanes, known as granulation, typical sizes of order 100 km.



These features are associated with the convective upwelling of hotter material from below. In sunspots that process is inhibited by magnetic fields so that the surface temperature is lower and that area looks dark in comparison to the rest of the photosphere. Granulation is the visible appearance of the tops of the upwelling convective cells.



However, these phenomena are short-lived compared with the GRS on Jupiter. Sunspots have lifetimes of maybe a month or two and then the magnetic fields are reordered by the Sun's differential rotation and sheared apart. Granulation is ever present but the detailed pattern shifts on timescales of hours as different convective cells rise and fall.

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