Using a new 1-m telescope on the island of La Palma in the Canary Islands, solar astronomers from the Royal Swedish Academy of Sciences in Stockholm have investigated heretofore-unseen structures in sunspots. The Swedish-designed and -built instrument, which features adaptive optics and other technologies to compensate for atmospheric blurring, offers the ability to image solar features with a resolution of better than 0.12 arc sec.Reporting in the Nov. 14 issue of Nature, the scientists, from the Institute for Solar Physics, describe dark cores that are less than 90 km in width and more than 1000 km long within bright penumbral filaments. Current theories and models have not predicted the structures, they note, and the phenomena may lead to a better understanding of solar magnetohydrodynamics.