Understanding the Absence of Poisson Spot in Solar Eclipses

A recent paper by Jami J. Kinnunen explores the absence of a Poisson spot during solar eclipses, a phenomenon that has intrigued physicists and educators alike. The Poisson spot, also known as the "dark spot" or "Arago spot," is a bright point that appears at the center of a circular shadow cast by a spherical object. This phenomenon is typically observed in cases involving point light sources and spherical objects, leading to questions about its visibility during solar eclipses.

Kinnunen applies the Huygens-Fresnel diffraction model to analyze why the Poisson spot does not manifest in solar eclipses. The study suggests that the simple model of light passing just outside a spherical object, which successfully predicts the Poisson spot in other contexts, fails in the case of solar eclipses due to the complex interactions of light waves with the sun's atmosphere and the moon's surface.

The findings have implications for physics education, particularly in how concepts of light and shadow are taught. Understanding the conditions under which the Poisson spot appears or disappears can enhance the educational discourse surrounding optics and wave phenomena. The paper has been accepted for publication in the American Journal of Physics, indicating its relevance to both academic and educational fields.

For those interested in further details, the full paper can be accessed at arXiv:2408.13894.