THE PLANET OF LOVE.

THE contrast between Venus and Jupiter (two orbs which often seem so strikingly alike that only their position distinguishes one from the other) is in reality most complete. It is difficult even for the astronomer to realise the fact that of these orbs one is thirteen hundred times larger than the other, that the surface of the lesser is illuminated some fifty times more brilliantly than that of the farther and greater. It requires, too, a strong effort of the imagination to picture to oneself that one orb is solitary, like Mars or Mercury, while the other is circled round by four orbs, the least of which is as large as our moon.

It may be interesting to consider some of the facts which astronomers have learned respecting the beautiful planet which appropriately bears the name of the loveliest of the heathen goddesses. There is much, indeed, in what is known about Venus which rather tends to disappoint than to satisfy the questioner; much also which is more fitted to invite speculation than to afford any basis for sound theorizing. When we compare what has been learned about Venus with the detailed information which the telescope has given us respecting Mars, or with the grand phenomena

whose progress has been traced in the distant orbs of Jupiter and Saturn, we are apt to feel astonished that the planet which approaches us most nearly should have revealed so little, even under the most searching scrutiny. Yet it is only by comparison with what has been learned about these most interesting orbs that our information about Venus seems small in amount. In reality there is much which will very well repay our attention, more especially when we consider Venus not merely with reference to what the telescope teaches us respecting her, but also in relation to her position in the scheme of worlds circling around the

sun.

It used to be supposed that Venus is rather larger than our own earth. But more careful measurements made in recent times have shown that she is in all probability considerably smaller than the earth. A circumstance had tended to deceive the earlier telescopists. Venus shines with such exceeding brightness as to appear larger than she really is. The fact that bright objects are thus seemingly enlarged is doubtless familiar to most who read this paper. It is strikingly illustrated by the appearance which the new moon presents when the unenlightened half of her globe is visible, or when the old moon is in the new moon's arms.' 6 dark part appears to belong to a smaller globe than the bright crescent; yet, in reality of course, the effect is but an optical illusion. Indeed, quite recently astronomers had to reduce their estimate of the moon's size on account of the very effect I am here referring to.

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In the case of Venus the effect is, of course, more remarkable, especially when considered as affecting Venus's bulk; for she shines much more brilliantly (though of course giving out very much less light altogether) than the moon; and being so much farther away, the same amount of seeming extension outwards corresponds in reality to a much greater error in the estimated diameter. Thus it happens that in Ferguson's Astronomy' we find the diameter of Venus set down at 7,906 miles, while Sir W. Herschel and Arago set it at 8,100 miles; whereas the estimate now generally regarded as most trustworthy assigns to her a diameter of only 7,500 miles. Thus her estimated bulk has been very considerably diminished; for though her diameter has been reduced but by about one-sixteenth part from Ferguson's estimate, it is easily calculated that her volume has been reduced by fully a seventh part-in which degree, also, it falls short of the earth's. Her surface, which is perhaps a more important feature when we consider her as the probable abode of living creatures, is less than the earth's in the proportion of about nine to ten.

Still, it is hardly necessary to point out that these differences are very slight when compared with those which distinguish the other planets of the solar system from our own earth. Mars, with his diameter of but 4,500 miles, on the one hand, and Uranus, with a diameter of more than 35,000 miles, on the other, seem startlingly unlike our earth after the relations of

Venus have been considered; and yet they come next to her in this respect. We have to pass from Mars to small Mercury and the asteroids in following the descending scale of magnitude, and from Uranus to Neptune, the ringed Saturn, and the mighty mass of Jupiter, in following the ascending scale. In the whole range of planetary bodies, from Jupiter, more than twelve hundred times bulkier than our earth, down to the least asteroid-a globe, perchance, not larger than Mr. Coxwell's balloon-we meet with not one orb which can be regarded as our earth's twinsister world, save that globe alone whose glories now illuminate our evening twilight skies.

In one respect only the comparison fails. Unlike our earth, Venus has no moon. I shall not enter here into a consideration of the very singular circumstance that many observers, and some of them not unknown for skill and clear-sightedness, have declared that Venus has a moon and that they have seen it. Astronomers are now agreed that these observers were deceived, and I suppose little doubt can remain in the minds of all who are competent to weigh the evidence that Venus has no satellite. Still there are few chapters in the history of Astronomy more suggestive than that referring to the supposed discovery of a secondary orb, which has, in reality, no existence. Sir William Herschel's temporary belief in the existence of two rings at right angles to each other around the planet Uranus can by no means be compared with the strange deception which deluded observers in the case of

Venus. For Uranus is so far off that his phenomena are seen only with extreme difficulty; and the telescope with which Sir William Herschel chiefly studied the planet was notoriously imperfect as a defining instrument, notwithstanding its wonderful light-gathering power. It bunched a star into a cocked hat,' we are told, and in effect it made the rings round Uranus which for a time perplexed the great astronomer. But in the case of a planet so near to us, and so bright as Venus, one would have thought an optical illusion, such as the telescopic creation of a satellite, was wholly impossible. Here was an orb of which its observers felt able to say that its diameter was about one-fourth of Venus's, its light slightly inferior to hers in brightness, and its seeming shape horned, or gibbous, exactly as her own at the time of observation. And yet that orb was a mere moon-ghost, an unreal telescopic vision.

We shall inquire farther on, however, whether the want of a moon necessarily renders the skies of Venus at night dark and gloomy by comparison with ours, or, at least, with our moonlit nights.

The chief difficulty which the telescopist meets with in trying to examine the surface of Venus arises from the excessive brightness with which she is illuminated. Of course, I am not here referring to that splendour which the unarmed eye recognises in her light. Jupiter, when seen on the dark background of the midnight sky, shines with a splendour fairly comparable with that of Venus; and yet rather