Round the year with the stars / The chief beauties of the starry heavens as seen with the naked eye

by Garrett Putman Serviss

The charts illustrating this book have been drawn by the writer especially to meet the needs of beginners—of those who, feeling what a void in their intellectual life ignorance of the stars has created, would now fill that void, and thus round out their spiritual being with some knowledge of Nature on her most majestic and yet most beautiful and winning side.

On account of the necessarily diminutive scale of the charts, everything has been omitted from them which did not seem essential. But for the purpose in view they gain by this process of exclusion, for with more details they would have been confusing. It is the broad, general aspect of the sky with which the beginner must first familiarize himself. At the start the heavens appear to him to be filled with an innumerable multitude of scintillating sparks, scattered everywhere in disorder. But with a little attention he perceives that there is discipline in this host, and immediately the discovery gives him pleasure and awakens his admiration, as the perception of order always does. The great leaders of the firmament come forth, unmistakable, plainly recognizable, and thereupon the rank and file fall into their places. Then the ineffable beauty of the whole assemblage bursts like a revelation upon the mind. This revelation is not for the dull in spirit, but he who has once had it becomes henceforth, and even in spite of previous prejudice or indifference, a devotee of the stars, with a zeal flaming brighter with every swing of the pendulum of his years.

In the four circular charts representing the aspect of the heavens respectively at the Vernal Equinox, the Summer Solstice, the Autumnal Equinox, and the Winter Solstice, few stars fainter than the fourth magnitude are included, and not all even of that magnitude, because the sole purpose is to enable the beginner to recognize the constellations by their characteristic groupings of stars and their relative situations in the sky. The insuperable difficulty is to picture the hemispherical sky on a flat page. A certain amount of distortion cannot be avoided, and the reader’s imagination must supply the effect of perspective. He must always remember that the centre of the chart stands for the middle of the sky overhead, and that the circular boundary represents the full round of the horizon, from east through south, west, and north, to east again. If he is comparing the chart with the sky while facing south, he should hold the chart upright as it is printed in the book; if he makes the comparison while facing north, he should turn the chart upside down. If he lies on his back with his head to the north (and in no other way can one get so vast an impression of the starry dome), and holds the chart over his head, it will represent the entire vault of the firmament.

The names of the constellations will be found on the charts, and also the individual names of the most celebrated stars, but the constellation boundaries are not shown, because, in nine cases out of ten, the precise limits of a constellation are not important for the beginner to know, and to search for them would simply lead to confusion. As he progresses in his knowledge of the sky any uncertainty about the constellation to which particular stars belong can be settled by consulting the six charts, drawn to a larger scale, at the end of the book. On these charts more of the small stars are shown, and in addition there will be found the Greek letters which astronomers attach to the principal stars of each constellation for the sake of ready identification. On these charts, too, the constellation boundaries will be seen, indicated by dotted lines. The tracing of these lines is more or less a matter of arbitrary choice. There are no international boundary disputes among the heavenly powers, and the frontier lines may run anywhere, provided only that they do not include in one constellation any stars which by common usage, or prescription, belong to another. The constellations have been reshaped many times in the past. The “geography of the heavens” has known as many changes as that of the earth, the ambition of the old astronomers being sometimes as insatiable as that of founders of terrestrial kingdoms and empires. About three centuries ago the starry sky was “Christianized,” St. Matthew, St. Peter, St. John, St. Joseph, St. Michael, St. Stephen, St. Gabriel, St. Mary Magdalen, St. Katharine, together with Noah, Aaron, Job, and Eve, taking the places of the heathen gods, goddesses, and heroes in the sky, while Saturn became Adam, Jupiter Moses, Mars Joshua, Mercury Elias, Venus St. John Baptist (!), the Moon the Virgin Mary, and the Sun Christ (see [Appendix]). It is not an unheard-of thing in uranography (“description of the heavens”; analogue to geography) for a star, or a group of stars, to change allegiance, or even to belong to two constellations at the same time. The bright star Alpheratz is still an example of this double nationality, for, although it shines on the head of Andromeda and is her jewel par excellence, yet her neighbor Pegasus also lays claim to the star, and uranographers so far admit the justice of his claim that they call Alpheratz, according to circumstances, either Alpha (α) Andromedæ or Delta (δ) Pegasi.

For many of their purposes astronomers find no use for the constellations, preferring to identify the stars by their position in right ascension and declination (equivalent to longitude and latitude), and in the great modern Durchmusterungs, or star catalogues, this plan is universally followed. Still, the constellations afford a very convenient classification of the stars, and probably they will never be abandoned even by professional astronomers; while from another standpoint they never can be abandoned, because they are among the most ancient and precious of human documents, valuable for history and for the understanding of mythology, and resistlessly charming in their poetic associations.

But, to return to the description of the charts, the reader should be informed as to the meaning of the lines shown upon them, and of the indications found round their borders. In the four circular charts the closed curve crossing the sky from right to left represents the equator of the heavens, which is directly over the equator of the earth; the vertical line through the centre shows the meridian, or north and south line, which, so to speak, follows the observer wherever he may go, occupying the same place in the sky, at the same hour of local time, in all longitudes; and the dotted curve is the ecliptic, or the apparent annual path of the sun through the sky. The crossing points of the equator and the ecliptic are respectively the Vernal and the Autumnal Equinox, where the sun is at the two dates in the year when day and night are of equal length; and the farthest northern and southern points of the ecliptic are respectively the Summer and the Winter Solstice, where the sun is at the times of the longest and the shortest days in our hemisphere. These four fundamental points are all shown on the charts. Around the border the hours of right ascension are indicated by Roman numerals. Each hour corresponds to 15° of space, or one twenty-fourth of a circle of the sphere. The hours begin at the Vernal Equinox, which is graphically described as the “Greenwich of the Sky.”

In the larger-scale charts at the end of the book the hours of right ascension are indicated at the bottom, and the degrees of north and south declination (the sign + standing for north and - for south) are shown at the side. In both cases the declination is reckoned from the equator. The four oblong charts of this series, taken together, represent the entire circuit of sky between 40° north and 40° south declination, and the two semicircular charts, taken together, show the stars within 50° of the north pole. Thus the entire set of six charts exhibits the complete dome of the heavens from the north pole to 40° south declination. In passing from the oblong to the semicircular charts it is only necessary to bring the hours of right ascension into accord. In the semicircular charts the hours will be found round the curved borders.

Each of the four circular charts in the body of the book represents the aspect of the evening sky at one of the equinoctial or solstitial epochs. To be more precise, these charts show the sky as it appears, at about the latitude of New York, at 10 P.M., on, respectively, March 20th (the Vernal Equinox), June 21st (the Summer Solstice), September 23d (the Autumnal Equinox), and December 22d (the Winter Solstice).

But the reader must not think that it is necessary to confine himself to the exact latitude, date, or hour just mentioned. Undoubtedly it would be better for the beginner to do that approximately, but it is not essential. The effect of a change of latitude is, perhaps, the least important. If the observer is farther south than about 40° north latitude, the southern stars will appear higher in the sky than they are shown in the charts, and some of the stars close to the northern horizon will sink from view. If, on the other hand, he is farther north (as in Canada or Northern Europe), the northern stars will appear higher, and some of those near the southern horizon will be invisible. But if he confines his attention to the stars and constellations represented in the central parts of the charts (which he should, in any case, do for other reasons), the effect of the shift due to difference of latitude will not be found very serious.

As to the effects of a departure from the hours and dates for which the charts are drawn, they, too, can readily be allowed for. Suppose that, without changing the date, the reader makes his observations an hour earlier than that given, say at 9 P.M., March 20th. Then he will find that some of the eastern stars, seen along the left-hand edge of the chart when it is held upright, have not yet come into view above the horizon, while other stars, not seen on the chart drawn for that date, are visible above the horizon in the west. To the stars thus carried out of, or brought into, view he should pay no attention; he will find them again on other charts when they are better placed for observation.