Venus.
Venus is the planet next in order, and revolves about 66,000,000 of miles from the sun. It is the nearest planet to the earth, and is somewhat smaller than the latter. This planet is both a morning and evening star, and is very brilliant—so much so, that any close observation with the telescope is not possible; and when at her nearest point she is invisible as she passes between us and the sun, and of course when fully illuminated she is directly beyond the sun, and enclosed in his rays. But under other circumstances she is distinctly visible as a crescent in the evening, and nearly full as a morning star. Venus goes round the sun in 224 days, and her day is rather less than ours.
Fig. 578.—Orbit of Venus.
Venus has long been celebrated as the morning and evening star, as “Lucifer” and “Hesperus.” “Lucifer, son of the morning,” is mentioned by Isaiah. That Venus possesses an atmosphere denser than our own can scarcely be doubted. The observations made during the successive transits, particularly the last (1874), seem to have established the fact that aqueous vapour exists around, and water in, Venus. No satellite can be found, though the ancients reported such an attendant upon this planet.
The apparent diameter of Venus varies considerably in consequence of her varying distances at the inferior and superior conjunction. When nearest the earth, if she presented her fully illuminated disc to our gaze, we should see a miniature moon, and even under the circumstances Venus throws a shadow, so brilliant is her light.
Fig. 579.—Venus, at quadrature.
The transits of Venus have been referred to, and, like those of Mercury, are simply a passing, or “transit,” of the planet across the illuminated disc of the sun. The transits afford means to ascertain the volume and distance, etc., of the sun, and this year (1882) the next transit is expected. There will not be another for more than one hundred years.
