Why is there no Poisson spot in a solar eclipse?

TL;DR

This paper investigates the absence of a Poisson spot during a solar eclipse by applying the Huygens-Fresnel diffraction model to understand the underlying optical phenomena.

Contribution

It provides a detailed diffraction-based explanation for why the Poisson spot does not appear in solar eclipses, addressing limitations of simpler models.

Findings

Huygens-Fresnel model explains the absence of Poisson spot in solar eclipses.

Simple models considering only light passing outside the object are insufficient.

Diffraction effects prevent the formation of the Poisson spot in this context.

Abstract

The Poisson spot is a fascinating lecture demonstration. Its simple explanation can lead to further questions, not only the one posed in the title, but also questions such as why the simple model that considers only light passing just outside the spherical object is successful. The Huygens-Fresnel diffraction model is applied to answer these questions.