Identity of the Great Red Spot relative to Cassini’s Permanent Spot (1665–1713)

Ascertain whether the Great Red Spot first observed in 1831 is identical to the "Permanent Spot" reported by Giovanni Domenico Cassini and other astronomers between 1665 and 1713 at the same latitude, by establishing continuity or discontinuity across the 1713–1831 observational gap using size, drift rate, morphology, and presence.

Background

Historical observations record a dark oval, the Permanent Spot (PS), at the GRS latitude from 1665 to 1713, followed by a ~118-year interval without reports before features characteristic of the current GRS reappeared in 1831. The longevity and continuity of the GRS across this observational gap have been debated.

The authors conduct a comprehensive analysis of historical drawings, photographs, and modern images, measuring sizes, eccentricities, areas, and drift rates of the PS, the GRS, and the Hollow. Their evidence suggests PS is unlikely to be the current GRS, yet the question is explicitly framed as unclear in the introduction, reflecting the enduring uncertainty in the historical identity prior to their analysis.

References

And its longevity is a matter of debate, and to date it is not clear if the GRS was the dark oval, nicknamed Permanent Spot (PS), reported by Giovanni Domenico Cassini and others from 1665 to 1713 (Cassini, 1666; Chapman, 1968; Falorni, 1987; Rogers, 1995; Hockey, 1999; Simon, 2016) (Fig. 1, Fig. S1).

— The Origin of Jupiter's Great Red Spot  (2406.13222 - Sánchez-Lavega et al., 2024) in Section 1. Introduction