The existence of snow at the poles of Venus has been suspected by observers of tried skill and experience such as Phillips and Webb, though the idea was first broached by Gruithuisen in 1813. Flammarion’s observations during 1892 and the two following years are distinctly confirmatory of this idea. He adds that as both polar caps are visible at the same time the planet’s axis cannot be much inclined to the plane of its orbit.
Compared with all the other planets the absolute brightness of Venus stands very high. Of course it must be understood that by this phrase “absolute brightness” no more is meant than its reflective power. Venus is what it is by virtue of its power of reflecting Sun-light; presumably it has no inherent brightness of its own. What its reflective power is was probably never more effectively brought under the notice of a human eye than on September 26, 1878, when Nasmyth enjoyed an opportunity of seeing Venus and Mercury side by side for several hours in the same field of view. He speaks of Venus as resembling clean silver and Mercury as nothing better than lead or zinc. Seeing that owing to its greater proximity to the Sun the light incident on Mercury must be some 3½ times as strong as the light incident on Venus, it follows that the reflective power of Venus must be very great. As a matter of fact it has been calculated to be nearly equal to newly fallen snow; in other words to reflect fully 70 per cent. of the light which impinges on it.
Venus has no satellite; this fact seems certain. Yet half a dozen or more observers between 1645 and 1768 discovered such a satellite; observed it; followed it! This startling mystery, as it really was, attracted some years ago the attention of a very careful Belgian observer, Stroobant, who examined in a most painstaking manner all the recorded observations. His conclusions were that in almost all cases particular stars (which he identified) were mistaken for a satellite. Where the object seen was not capable of identification, possibly it was a minor planet; whilst in one instance it was probable that it was Uranus which had been seen and regarded as a satellite of Venus.
Venus is perhaps the planet which has most impressed the popular mind. For the earliest illustration of this statement we must go as far back as Homer who makes two references to it in the Iliad. These, in Pope’s version, run as follows:—
“As radiant Hesper shines with keener light,
Far beaming o’er the silver host of night.”
—xxii. 399 [318].
“The morning planet told th’ approach of light;
And fast behind, Aurora’s warmer ray
O’er the broad ocean pour’d the golden day.”