Sunspots during the Maunder Minimum from Machina Coelestis by Hevelius

TL;DR

This study revisits Johannes Hevelius's 17th-century sunspot observations from Machina Coelestis, providing translations, context, and an estimate of solar activity during the Maunder Minimum that suggests higher sunspot numbers than previous reconstructions.

Contribution

It offers a detailed translation and contextual analysis of Hevelius's sunspot records and provides an independent estimate of solar activity during the Maunder Minimum based solely on these observations.

Findings

Estimated sunspot numbers are very low, consistent with a grand solar minimum.

The sunspot numbers derived are higher than those in previous reconstructions for the same period.

The study enhances historical solar activity records with new translations and context.

Abstract

We revisited the sunspot observations published by Johannes Hevelius in his book Machina Coelestis (1679) corresponding to the period 1653-1675 (just in the middle of the Maunder Minimum). We show detailed translations of the original Latin texts describing the sunspot records and provide the general context of these sunspot observations. From this source only, we present an estimate of the annual values of the Group Sunspot Number based only on the records that explicitly inform about the presence or absence of sunspots. Although we obtain very low values of the Group Sunspot Number, in accordance with a grand minimum of solar activity, these values are significantly higher in general than the values provided by Hoyt and Schatten (1998) for the same period.