Large-scale Morphology of the Optical F-corona from a Total Solar Eclipse Observation During the Artemis II Lunar Flyby

TL;DR

This study analyzes the optical F-corona's morphology during a total solar eclipse captured in a wide-field image, revealing its elliptical shape and radial brightness profiles, and compares findings with existing models.

Contribution

It demonstrates the feasibility of analyzing the F-corona's structure from eclipse images without full photometric calibration, validating the approach with stellar calibration and comparison to models.

Findings

F-corona exhibits a flattened, elliptical morphology aligned with the ecliptic plane.

Radial intensity profiles follow power laws with steeper slopes than previous observations.

Model comparison supports a dust density power-law index of approximately 1.3.

Abstract

We investigated the structure of the optical F-corona, i.e., inner zodiacal light, using a publicly released wide-field image of a total solar eclipse that was obtained during the Artemis~II crewed lunar flyby. In this image, the solar disk is fully occulted by the Moon, providing a rare view of diffuse circumsolar emission over a wide angular extent. Although the dataset is derived from a rendered RGB JPEG image without full photometric calibration, the gamma correction inherent to the image format was explicitly accounted for and the instrumental response was validated using field stars. The stellar calibration demonstrates a linear response within the unsaturated regime relevant to our measurements, enabling a reliable analysis of the relative morphology and brightness profiles of the F-corona. The observed F-corona exhibits a flattened, nearly elliptical morphology aligned with the ecliptic plane, with flattening indices of 0.52, 0.54, and 0.56 for the red, green, and blue channels, respectively. Radial intensity profiles along ecliptic longitude and latitude are well described by power laws in solar elongation, although the derived slopes are systematically steeper than previous observations. Comparison with the ZodiSURF zodiacal light model indicates that the observed radial profile of the F-corona along the ecliptic longitude is modestly reproduced by the model, supporting a radial dust number-density power-law index of $\alpha$ ~1.3, even in regions near the Sun. In a broader historical context, these results provide an empirical proof-of-concept that supports future solar coronal occultation observations from lunar orbit.