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Astronomy/Describe what the Sun would look like from Earth if the entire photosphere were the same temp. as a sunspot?


Describe what the Sun would look like from Earth if the entire photosphere were the same temperature as a sunspot?


The range of sunspot temperatures is from 3000 K - 4500 K, while the normal photosphere is approximately 5800K. With the latter surface temperature the Sun radiates as a yellow dwarf star of spectral class G (specifically G2). If all the photosphere were reduced to the median temperature of a sunspot (say to 3750 K) the Sun would appear as a red star with an M spectral class.

Note: It would not be correct to call the Sun a "red dwarf" after such change as you prescribe, because although it may share the same temperature and spectral class as red dwarfs, its mass would be a lot larger (red dwarfs typically don't reach more than 50% of the solar mass.


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Philip Stahl


I have more than forty years of experience in Astronomy, specifically solar and space physics. My specialties include the physics of solar flares, sunspots, including their effects on Earth and statistics pertaining to sunspot morphology and flare geo-effectiveness.


Astronomy: Worked at university observatory in college, doing astrographic measurements. Developed first ever astronomy curriculum for secondary schools in Caribbean. Gave workshops in astrophysics and astronomical measurements at Harry Bayley Observatory, Barbados. M.Phil. degree in Physics/Solar Physics and more than twenty years as researcher with discovery of SID flares. Developed of first ever consistent magnetic arcade model for solar flares incorporating energy dissipation and accumulation. Develop first ever loop solar flare model using double layers and incorporating cavity resonators.

American Astronomical Society (Solar Physics and Dynamical Astronomy divisions), American Mathematical Society, American Geophysical Union.

Solar Physics (journal), The Journal of the Royal Astronomical Society of Canada, The Proceedings of the Meudon Solar Flare Workshop (1986), The Proceedings of the Caribbean Physics Conference (1985). Books: 'Selected Analyses in Solar Flare Plasma Dynamics', 'Physics Notes for Advanced Level'. 'Astronomy and Astrophysics: Notes, Problems and Solutions'.

B.A. Astronomy, M. Phil. Physics

Awards and Honors
American Astronomical Society Studentship Award (1984), Barbados Government Award for Solar Research (1980), Barbados Astronomical Society Award for Service as Journal Editor (1977-91)

Past/Present Clients
Caribbean Examinations Council, Barbados Astronomical Society, Trinidad & Tobago Astronomical Society.

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