Abstract
PERIODIC VARIATIONS IN THE LATITUDE OF SOLAR PROMINENCES.—From a paper by Prof. Ricci, in Comples rendus for August 3, it appears that the mean latitude of solar prominences varies periodically in the same way as that of spots. During the last eleven years observations of the form, position, and dimension of solar prominences have been made at Palermo on 2207 days, with the same refractor and spectroscope. In this period 7663 prominences have been observed, having a height equal to or greater than 30”. Neglecting a few irregularities, the observations show that about the time of maximum solar activity prominences occur nearest the sun's equator; the mean latitude for both hemispheres in the second year after the last maximum being 27°5. There is then a rapid general increase in the latitude of most frequent occurrence up to the minimum epoch, the mean latitude for both hemispheres in the year following the last minimum—that is, in 1890—being 41°3. In other words, up to the commencement of the minimum period prominences approach the equator. They then appear in high latitudes, to descend again to the equator in an eleven-year cycle. The intimate relation that exists between this variation and that observed in the distribution of spots is evident from an inspection of the accompanying figure, which represents the mean latitudes of spots according to Prof. Spörer's observations, and those found for prominences by Prof. Riccò. The pairs of like curves run almost parallel to each other, and are separated by an. approximately equal number of degrees at all points. It is. worthy of remark that the photographs of the solar corona recently investigated by Prof. Bigelow exhibit a movement in latitude which is most probably connected with the latitude variations of sun-spots and prominences.
Article PDF
Rights and permissions
About this article
Cite this article
Our Astronomical Column. Nature 44, 391–392 (1891). https://doi.org/10.1038/044391a0
Issue Date:
DOI: https://doi.org/10.1038/044391a0