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Ordinarily speaking, it is a bright star of the second magnitude, and, whatever be the cause, the star performs its variations with marvellous uniformity. In fact, Algol has always arrested the attention of those who observed the heavens, and in early times was looked on as the eye of a demon. There are many other stars which also change their brilliancy.
The diameter of Algol is believed to be about 1,125,000 miles, that of the dark body about 840,000 miles, and the mean distance from center to center 3,230,000 miles. The density of both the light and the dark star is slight compared with that of the sun, so that their combined mass is only two thirds as great as the sun's.
It is a large dark body, very nearly as large as Algol himself, and if, as we may conjecture, it is a mighty planet, we have the extraordinary example of a planet and its sun being nearly the same size.
The period of revolution is identical with the period of Algol's cycle of variation, and the diminution of light is caused by the interposition of the dark body as it sweeps along that part of its orbit lying between our point of view and the disk of Algol. In other words, once in every two days twenty hours and forty-nine minutes Algol, as seen from the earth, undergoes a partial eclipse.
One very well-known variable star you can see for yourselves, and as an ounce of observation is worth a pound of hearsay, you might take a little trouble to find it. Go out on any clear starlight night and look. These are in the constellation called Perseus, and a little to the right of the middle and lowest one is the only variable star we can see in the sky without a telescope. This is Algol.
In 1889 Vogel, with the Potsdam spectrograph, actually found that the luminous star is receding before each eclipse, and approaching us after each eclipse; thus entirely supporting Goodricke's opinion. There are many variables of the Algol type, and information is steadily accumulating. But all variable stars do not suffer the sudden variations of Algol.
The time spent by light in crossing this orbit causes an apparent delay in the phases of the variable, when Algol and its eclipsing satellite are on its further side from ourselves, balanced by acceleration while they traverse its hither side. Dr.
There are many types, and the explanations of others have not proved so easy. The Harvard College photographs have disclosed the very great prevalence of variability, and this is certainly one of the lines in which modern discovery must progress. Roberts, in South Africa, has done splendid work on the periods of variables of the Algol type. New Stars.
It's a perfectly legitimate way of making a living." Hawkes' eyes hardened suddenly, and in a flat quiet voice added, "The way to stay out of trouble on Earth is to avoid being preachy, son. This isn't a pretty world. There are too many people on it, and not many can afford the passage out to Gamma Leonis IV or Algol VII or some of the nice uncluttered colony-worlds.
She raised herself feebly upon her elbow, and looked dazedly up at the cold, unfeeling stars that go on shining through the ages, making no sign of sympathy with human griefs. Perseus had risen to his meridian, and Algol, her natal star, alternately darkened and brightened as if it were the scene of some fierce conflict of the powers of light and darkness, like that going on in her own soul.