Andrew Cooper
Jul 19, 2022    Waikoloa, HI (map)
20cm f/6 Newtonian, Cave Astrola @ 76x
Seeing: 6 Transparency: 6 Moon: 0%

Brilliant orange, no companion noted

Captain William Henry Smyth
Jun 12, 1834    No. 6 The Crescent, Bedford, England (map)
150mm f/17.6 refractor by Tully 1827

Arcturus, a standard Greenwich star, between the legs of Bootes, with a distant companion in the nf quadrant. A 1, reddish yellow; B 11, lilac; and at the extreme verge of the field, under moderate magnifying power, is the star infra Arclurum, noticed by Flamsteed on the 14th of February, 1690, then preceding the primary, but now, from the large proper motions of Arcturus, following it. These motions have been well watched, and the best registers of their quantity and direction give the following values: in R.A. -1.17 Dec. -1.96" (Argelander).

Mayer of Manheim, who had some odd notions in astrognosy, considered Arcturus as a cluster; in the which he was mistaken. Various crotchets have been started respecting its insulation, while from its brilliance and proper motions, a conclusion was drawn that it was the nearest star to our system, but this has been abandoned since the still greater motion of 61 Cyni, μ Cassiopeia, and other stars, has been ascertained.

Dr. Hornsby pronounced upon its proximity, because the variation of its place seemed more remarkable than that of any other of the stars; and by comparing a variety of observations respecting its motions, he inferred that the obliquity of the ecliptic decreases at the rate of 58" in one hundred years; a quantity, he observes, ** which will be found nearly at a mean of the computations framed by Mr. Euler and M. de la Lande, upon the principles of attraction." Sanguine hopes of arriving at its distance were entertained, but every exertion met with disappointment; and Piazzi dismissed the case thus: "Pluries inquisivimus in hujus stellee parallaxim, sed nihil profecimus."

The star has, however, been extensively useful in modern astronomy; and it is remarkable as being the body by which the fine discovery was made, that stars and planets may be advantageously observed during the Sun's presence. The Abbé Picard imagined himself to be the discoverer of the feasibility of so doing, from observing the meridional altitude of this star on the 13th of July, 1669, while the Sun was elevated 17° but he who observes should also read, or he may "make many inventions," for the fact of the principal stars being visible in broad daylight had been announced by the enthusiastic M. Morin, in 1635, and, curiously enough, his first star was also Arcturus.

Sir William Herschel supposed the true diameter of this star to be about one-tenth of a second, having detected for the apparent, two-tenths. This would give as the diameter of Arcturus four millions of leagues, or eleven times the diameter of our Sun.

Arcturus is compounded of αρκτcrον, and ονρα, bear's tail, from its proximity to the latter, being somewhat in a direction pointed by a line drawn through the two hinder stars, ζ and η, of the tail. Being one of the most brilliant of the stellar bodies, it was noticed by very early star-gazers; but though, as I have said under η Tauri, the name is dragged into our translation of Job as a synonyme of 'Aïsh, it must be inferred that the Seventy wished rather to express a brilliant emblem of Majesty, than to be critically exact: like the exclamation of Job, "Oh that my words were printed in a book!" It is first mentioned by Hesiod, whose æra is nearly approximated by the passage in the Works and Days, in which the star is mentioned. From this passage it appears that there is a difference of 40 days in the achronical rising of that lucida, since the time of the poet; whence, by allowing 50" annually as the recession of the equinoxes, we obtain about 2800 years since the days of Hesiod.

― A Cycle of Celestial Objects Vol II, The Bedford Catalogue, William Henry Smyth, 1844