Sunspot engravings made in the Maunder minimum are used to evaluate the fine structure of sunspots. Based on 78 images of the full solar disk and 77 images of individual sunspots, we have evaluated the ratio of penumbra-to-umbra area (P/U) to be 4.2±2.5 and 3.8±2.3, respectively. These results are consistent with previous estimates before, during, and after the Maunder minimum, as well as with the P/U ratio observed in the largest sunspot groups in Solar Cycle 24. This suggests that the near-surface convection mode has most likely remained unchanged since the early seventeenth century. We also found that schematic sunspot drawings tend to underestimate the P/U ratio.
Original languageEnglish
Article number76
JournalSolar Physics
Volume300
Issue number6
DOIs
StatePublished - 1 Jun 2025

    Research areas

  • Observations; sunspots, Penumbra; sunspots, Solar cycle, Statistics; sunspots, Umbra

ID: 136417858