Abstract
THE accompanying sketch shows in a rough way the umbræ and a small portion of the penumbra of a sun spot that I observed on the 6th and 7th of this month, and which was made remarkable by the presence of a reddish-brown object like a cloud, that seemed to hang over the nucleus of the principal umbra, apparently dividing it in two. Could this object be seen without the intervention of the dark glass, it would doubtless show a bright red instead of a reddish-brown colour; and from its fog-like aspect, though it was well defined in outline and acuminated at both ends, the impression was inevitable that it hung at a certain altitude above the spot. However, it evidently had no motion distinct from the latter, as on the 7th it occupied the same position as on the day before, but it was much reduced in size. On the 8th it was seen no longer, and the nucleus was now in one, seeming to show pretty clearly that its previous apparent division in two was really caused by the intervention of the brown cloud suspended over it, and that the phenomenon did not consist of two distinct neuclei with the brown object lying between them. I am not aware that anything like this was observed before
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BIRMINGHAM, J. Remarkable Sun-spots. Nature 4, 102 (1871). https://doi.org/10.1038/004102b0
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DOI: https://doi.org/10.1038/004102b0
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