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XXIX.—On the Red Prominences seen during Total Eclipses of the Sun. Part I
Published online by Cambridge University Press: 17 January 2013
Extract
The red prominences seen during total solar eclipses, are conspicuous rose-coloured objects which appear round the dark edge of the moon, as soon as the last rays of the sun have disappeared. In preparing my account of the total eclipse of the 28th July 1851, it was at first my intention to have stated some hypothetical views which I had formed regarding those remarkable objects, and other appearances I had observed during the total phase of the eclipse. I found, however, that the mere description of phenomena extended to so great a length, as to render such a course inexpedient; and I have since delayed resuming the subject, in order that by comparing a number of other observations with my own, I might be enabled, either to confirm or to modify my views.
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- Research Article
- Information
- Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 20 , Issue 3 , 1853 , pp. 445 - 459
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- Copyright © Royal Society of Edinburgh 1853
References
page 446 note * Edinburgh New Philosophical Journal, Oct. 1851, p. 375.
page 446 note † Royal Ast. Soc. Notice, Jan. 1852, p. 54.
page 446 note ‡ Royal Ast. Soc. Notice, for Nov. 1842, p. 220.
page 446 note § Royal Ast. Soc. Notice, Jan. 1852, p. 47.
page 446 note ∥ M. Arago's highly interesting Account of the Total Eclipse of July 1842, in the Annuaire for 1846, contains ample evidence of the visibility of the red prominences to the naked eye. The following are some of the testimonies to that fact. M. Arago says, “A Perpignan, plusieurs personnes virent les protubérances à l'oil nu. Le fait n'est pas douteux.” (p. 412.) M. Flauguergues, who observed at Toulon, remarks, “Je n'avais point encore repris le télescope, lorsque je fus surpris par l'apparition d'un point lumineux rouge; puis, d'un second point semblable.” (p. 418.) M. Santini, who observed the eclipse at Padua, relates that several persons saw the prominences with the naked eye, (p. 427.)
I did not obtain access to M. Arago's admirable Memoir until after this paper had been read; otherwise I should have gladly availed myself more fully of its valuable contents than is now possible.
page 446 note ¶ “——Cette atmosphère conique [‘le cône d'ombre’] doit produire, dans ses couches successive, concentriques et de plus en plus froides, les phénomènes analogues aux réfractions qui s'opèrent près de I'horizon, en un mot, des phénomènes de mirage.” “Les montagnes roses qui apparurent alors [8 Juillet 1842], ne seraient autre chose que les images démesurément agrandies et déformées de quelques parties des montagnes lunaires, éclairées obliquement par le Soleil, et visibles à travers des vallées qui se trouvent çà et là, dans une direction favorable, sur le bord apparent de la Lune.”—Comptes Rendus de l'Academie, 4 Nov. 1850, p. 643.
page 447 note * Lecture by Mr Airy on the Total Solar Eclipse of 1851, July 28, p. 6.—Athenæum, No. 1230, p. 559.
page 447 note † Ast. Soc. Notice, p. 46.
page 447 note ‡ Ibid., p. 58.
page 447 note § Edin. New Phil. Journal, 1851, p. 375.
page 447 note ∥ An Account of the late Total Eclipse of the Sun, by R. C. Carrington, Esq., pp. 7, 10.
page 447 note ¶ Ast. Soc. Notice, p. 53.
page 447 note ** Ibid., p. 67.
page 448 note * Ast. Soc. Notice, p. 69; or Astronomische Nachrichten, No. 777.
M. Mayette at the eclipse of 1842, saw one of the red prominences after the sun had reappeared (quelques instantes apres l'emersion du Soleil.)—Annuaire, for 1846, p. 411; see also p. 421. M. Conti saw the prominences for a long time (per lungo tempo), after the reappearance of the sun; and M. Biela for some seconds, pp. 428, 429. The statement of the latter observer is particularly explicit. “Les premiers rayons du Soleil se montrerent en divers points séparés. Bientôt ces points se réunirents et formerent une lunule tres-déliée. Quelques secondes après la formation de cette lunule, les pyramides rougeâtres cesserent de se voir.”
page 448 note † May not the unequal heating of the air on the two sides of the path of the solar rays be the chief cause of the remarkable fluctuations in the sun's light, which have been observed at the beginning and end of the total phase of a solar eclipse? M. Savournin, an observer of the eclipse of July 1842, relates, “On a vu ici des ombres et des taches lumineuses courir les unes après les autres, comme paraissent le faire les ombres produites par de petits nuages qui passent successivement sur le Soleil. Ces taches n'étaient pas de la même couleur; il y en avait de rouges, de jaunes, de bleues, de blanches. Les enfants les poursuivaient et essayaient de mettre la main dessus. Ce phénomène extraordinaire fut remarqué quelques instants seulement avant la disparition complète du Soleil.”—Annvaire for 1846, p. 393. The strata of illuminated and dark air at the surface of the moons shadow, if their temperatures, and consequently their densities differ, cannot fail to mingle irregularly, and occasion fluctuating movements in the transmitted rays of light, similar to those which cause the dancing motion of objects seen through an ascending current of heated air, or through liquids of unequal densities which are in the act of mixing. This may also serve to explain the flickering appearance of the prominences noticed by some observers; which, from the terms used in describing it, was evidently not a permanent change of outline, but merely a fluctuation of their fcrms about a mean condition. Thus Mr Dawes and Mr Good, who saw on the moon's southern limb a long range of low prominences, both describe it as in motion. Mr Dawes, however, says, its regularities appeared permanent, and he ascribes its undulation to our own atmosphere.
page 449 note * Royal Ast. Soc. Notice, p. 43.
page 450 note * Astronomische Nachrichten, No. 777.
page 450 note † P. 337.
page 451 note * M. Arago observes, “Admettons un moment que les flammes étaient des parties intégrantes du Soleil,”—“Deux quelconques de ces flammes ayant été visibles dans deux stations différentes, à Montpellier et à Turin par exemple, ne purent manquer de s'y présenter dans les mêmes positions relatives et avec des formes identiques. Or les relations ne s'accordent pas toutes avec ce principe. Je m'empresse d'ajouter que la brièvéte du temps dont les astronomes purent disposer pour mesurer les protuberances, pour determiner leurs assiette, et par-dessus tout, que la surpris que chacun éprouva au moment d'une apparition si inattendue, durent beaucoup nuire à l'exactitude des observations.”—Annuaire for 1846, p. 453. The observers of the late eclipse, certainly cannot plead the surprise occasioned by an unforeseen appearance as a reason why their accounts of the red prominences are not more consistent. But I believe they will agree with me in thinking, that a closer coincidence cannot be expected in observations so hastily conducted, and where the phenomenon observed was one whose novelty and grandeur were fitted to excite the most powerful emotions.
page 451 note † Ast. Soc. Notice, pp. 53, 54.
page 452 note * Astron, Nachrichten, No. 787, p. 323.
page 453 note * In this estimation it is supposed that the breadth of the prominence was about two-thirds of its height, or 80“; an assumption which seems fully warranted by the drawings of the prominence given by most of the observers.
page 453 note † The drawings of the hook-shaped prominence in fig. 9, are all taken from the Royal Astronomical Society's Notice for January, with the exception of Mr Adie's, which is enlarged from the plate accompanying his account of the eclipse in the Edinburgh New Philosophical Journal.
page 454 note * While the causes now enumerated account sufficiently for much of the general diversity in the representations of the hook-shaped prominence, there are at the same time certain different types of form which may be observed among the drawings, and which can scarcely be referred to these causes. On comparing Nos. 2, 4, 7 with Nos. 8, 9, fig. 9, and also with fig. 8, it will be seen that the first three drawings are very like each other, as are also the last three, while there is little resemblance between the two sets. The first three represent the hook-shaped prominence as seen through rather large telescopes; the second, through small ones; and, as it is well known that certain telescopic objects vary greatly in appearance according to the instrumental power brought to bear on them, it may be worth inquiry, whether the same is not also the case with the red prominences.
page 455 note * Ast. Soc. Notice, pp. 67, 69; Edin. New Phil. Journal, Oct. 1851, pp. 365, 366.
page 456 note * Ast. Soc. Notice, p. 46.
page 456 note † Ib., p. 49.
page 456 note ‡ Ib., p. 50.
page 456 note § Ib., p. 53.
page 456 note ∥ Ib., p. 54.
page 457 note * Notice of R. Ast. Soc, p. 55.
page 457 note † Account of the late Total Eclipse of the Sun, by R. C. Carrington, pp. 6, 7, 10.
page 457 note ‡ “Le mouvements de ces dernières relativement au bord de la lune, et surtout l'éloignement successif de d du bord obscur, avec lequel je la vis premièrement en contact m'ont convainçu qu'elles appartenaient au Soléil.” The letter d refers to his drawing of the detached prominence. See Plate XI., Fig. 9., No. 6.—Manuscript Letter to the Author, dated 26th January 1852.
page 457 note § Ast. Soc. Notice, p. 60.
page 457 note ∥ Ib., p. 65.
page 457 note ¶ Ib., p. 67.
page 457 note ** Edin. New Phil. Journal, for October 1851, pp. 374, 375.
page 458 note * Ast. Nachricht, No. 777, p. 157.
page 458 note † P. 342.
page 458 note ‡ The occultation of the prominences on the east side by the advancing moon, serves to explain some of the variations in the statements of different observers, as to their number. Mr Lassell's observations already cited, shew that an observer might be too late on the outlook to see some of the prominences on the east side. Mr Dunkin, Mr Jackson, Mr Hind, Mr Pettersson, and myself, all saw no prominences to the east of the sun's vertex. At least three of these observers had their attention withdrawn from the red prominences by registering the time, and by making naked eye observations at the commencement of the total phase; while in Mr Dunkin's case, the sun was covered with a cloud shortly after the commencement of the totality, and the prominences were not looked for until after it had passed away.