Saturday, May 25, 2019

[rfaxqauf] Does the sun emit light equally in all directions?

Is the sun an isotropic radiator?

Probably yes at large scale.

Definitely no at the smallest scale: sunspots.

Maybe not at a medium scale: sunspots prefer certain latitudes: butterfly diagram.

Do sunspots make their local surrounding region brighter?  Somewhere must get brighter, because the sun as a whole is brighter at solar maximum despite lots of sunspots.

Of course, shadows cast by the planets (seen as transits by distant exoplanet astronomers) cause the solar system as a whole (not just the sun in isolation) to emit less light along the plane of the solar system.

It would be shocking to discover that the sun emits narrow beams of energy out its north and south poles like a neutron star, but we never knew about the beams because they were never pointed at us.  Do we know for certain that such beams do not exist?

If such beams were common in main sequence stars, we would have seen them in other stars, so the sun probably doesn't have them.  We also would have noticed comets grazing the poles of the sun light up more.

The sun is not a lambertian radiator: limb darkening.

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