The outermost 5% of the Sun lags the interior, and even within the photosphere itself there is a difference between the top layers and the bottom, even though there is no turbulence – it is very stable. Dust in interplanetary space is slowed down by collisions with solar photons, and the resulting loss of angular momentum slowly moves the dust particles towards the Sun. When a photon finally leaves the photosphere, it carries that momentum with it, imparting a significant torque on the Sun’s outermost surface.
Photons bounce around on their way out, gaining a small amount of momentum from each atom they ricochet off. As countless photons radiate from the Sun at different angles, the gas of the photosphere experiences a backward push. The push associated with each departing photon is minuscule, but over the Sun’s 4.5 billion year history, the barrage isn’t negligible. Over that time it would have caused a slowdown of about 3% in the rotation of the outermost 100 kilometres of the Sun (about 0.01% of its radius) and exerted a drag on the outermost 5%.
Ultimately our Sun seems to have to sacrifice something of itself in order to give life to the Solar System. It is right and good for living beings within the Heliosphere to consciously reflect light back to the Solar Source.
News Source: https://www.newscientist.com/article/2120202-suns-rotation-is-slowed-down-by-its-own-photons/
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