Venus, being farther from the sun, travels less rapidly. It reappears in the evening sky once in every 584 days, gradually withdrawing from the sun, and growing brighter until it reaches greatest eastern elongation, which may be as much as forty-seven degrees from the sun, after which it approaches the sun, still becoming brighter for several weeks, until at last it is lost in the glare of the sunlight. During its excursions in the evening sky (and the same is true of its morning apparitions), Venus becomes the most brilliant object in the starry heavens, so brilliant, in fact, that many persons can hardly be persuaded that it is not an artificial light, or some extraordinary phenomenon in space. In the telescope it shows (as does Mercury, also) phases like those of the moon, and when it is seen in the form of a narrow crescent it becomes one of the most charming objects imaginable. For more details about Mercury, Venus, and the other planets, the reader may consult _Astronomy with the Naked Eye_. Mars, Jupiter, and Saturn are more likely to cause confusion to the beginner by getting “mixed up” with the stars of the constellations he is studying, because they travel all round the sky, and may appear in turn in each of the zodiacal constellations at any hour of the night. The zodiacal constellations are twelve in number--Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricornus, Aquarius, and Pisces--and they lie in succession along the course of the ecliptic. Mars is not remarkably brilliant except when it is in opposition to the sun, which happens once every 780 days; but some of the oppositions are much more important than the average, because they occur when Mars is relatively near the earth. This planet is always distinguishable by its ruddy color. In case it is mistaken for a star, the error can be corrected by watching it for a few successive nights, when its motion will become clearly apparent. On the average it moves eastward about half a degree per day. Jupiter, always very conspicuous when in view, outshines even Sirius, though lacking the scintillation characteristic of that great star. Its light has a slightly yellowish tint, and is remarkably steady. Since it requires nearly twelve years to make a revolution round the sky, Jupiter’s motion is not immediately apparent. It remains for a long time in any constellation in which it may be found, travelling eastward, on the average, about 5′ of arc, or one-sixth of the apparent diameter of the moon, per day. In a month it moves about two and a half degrees. Saturn is yet more deliberate in its movements. Requiring almost thirty years for a revolution, it may remain more than two years in the same constellation, and its real motion will only become evident upon careful observation continued for several weeks.