by Various
CHAPTER XXI
OUR FIRST VIEW OF THE EARTH FROM MARS--A MARTIAN COURTSHIP
Within a few days we had our first glimpse of the earth from Mars. It appeared only as a very thin but bright crescent of light, as the lighted portion was less than one-twelfth part of the whole diameter of the disc, and it was only visible for a very short time.
Owing to the clear and thin atmosphere of Mars there is very little scintillation of the stars, and the crescent form of the earth at such periods as the present can plainly be discerned without the aid of a glass. To the Martians this is more readily seen than by us, as their eyes, being larger than ours, have a much greater light grasp.
For the same reason all the stars shine much brighter than they do in our skies, and many of the smaller ones which can be seen from Mars with the unaided eye, would here require a low power-glass to render them visible to us. The fact that Saturn has a ring is quite apparent to the Martian eye.
Day by day after this we saw the lighted area extending upon the earth, just the same as on the earth Venus can be seen with a telescope gradually to pass from the crescent phase to the gibbous form, and ultimately become full. Our earth is a morning and evening star to Mars the same as Venus is to the earth, according to its position with regard to the sun.
Whilst we were looking at the earth, I asked Merna "Whether he had ever seen the earth transit the sun as we occasionally see Venus or Mercury do so?"
He answered that "He carefully observed the last transit, which occurred on a date equivalent to our 8th May 1905, and was very interested in watching the earth pass, as a small black spot, across the sun's disc. The moon did not commence to cross until 6 hours and 7 minutes later, by which time the earth had passed over three-quarters of the sun's diameter. The earth was 8 hours and 42 minutes in transit, and the moon, which crossed a little lower down, was 8 hours and 31 minutes in crossing."
"That must have been an interesting sight," said John, "and I should like to have the opportunity of watching a similar transit."
"I am afraid you never will," said Merna, "for the transits only occur at long intervals. The previous transits occurred in November 1879, November 1800, May 1700, and May 1621. There will not be another until May 1984, and the next after that will not occur until November 2084."
"I am sorry to hear that," remarked John, "for even if I stayed here, I should not be likely to live long enough to see the next transit. Possibly you may do so, Merna; you are so much younger than I am."
"Yes," Merna replied, "it is not unlikely that I may see another such transit, for the average length of our lives on Mars is about equal to one hundred and thirty of your years, so that leaves me an ample margin of time."
I then went on to remark that as another result of the thinness of the Martian atmosphere twilight is much shorter than on the earth, the light being less diffused when the sun is below the horizon, and refraction also considerably less than we experience.
In this connection, I mentioned to M'Allister that we can often see the sun and the moon apparently above the earth's horizon when they are, in fact, below it. This is caused by the refractive power of our dense atmosphere, which has the effect of making both the sun and the moon appear a little higher up than they really are.
"That is something new to me, Professor," exclaimed M'Allister; "and I cannot say I quite understand how refraction, as you term it, has the effect you mention."
"It may help you, then," I answered, "if I tell you that water acts very much in the same way; and there is a simple and fairly well-known experiment you might try for yourself, which would make the matter perfectly clear to you. It is as follows:--
"Take a teacup and place a shilling at the bottom of it, then move back until you quite lose sight of the coin. Ask some one to pour some clean cold water gently into the cup, and, as it fills, the refraction of the water will apparently reduce the depth of the cup, and thus bring the coin fully into view. In much the same way the refraction of the atmosphere enables us to see the sun or the moon when those bodies are actually below the horizon."
"Thank you, Professor," said M'Allister; "I will try that little experiment at the first opportunity."
I then told him that at the time when the moon is just full it may rise towards the east just as the sun sets towards the west. Both orbs cannot be wholly above the horizon at the same time on such occasions, but, owing to refraction, we are able to see them both.
The sun and moon both appear flattened or oval-shaped just as they are rising or setting, in consequence of the effects of atmospheric refraction. These effects are usually most noticeable near the horizon, because the object is seen through the densest layers of air. But we never see a star in its true place in the sky, because the rays of light which come to us from the star are bent or refracted as they pass through our atmosphere, just as a stick appears to be bent when thrust down into a deep pool of clear water.
All these effects, however, add to the work of astronomers, because they must be taken into account in connection with their calculations.
* * * * *
As the time passed on, I day by day became more interested in Merna's relations with Eleeta.
"All the world loves a lover," and we elderly people are always pleased to note the progress of young folks' love affairs, especially if either of them is a relative of ours. In them we seem to renew our youth, for their entrancements seem to carry us back to the halcyon days when we ourselves were young. When "Love took up the glass of time and turned it in his glowing hands" everything seemed of a roseate hue, and we dwelt in the seventh heaven of delight, at peace with all the world and envying no one--for were we not the most happy and fortunate of mortals!
And then, to look upon a Martian courtship! To see the rich flushes mount to the cheeks of the lovers--their softly glowing luminous eyes, their absorbed attention in each other, and their mutual deference and response to the most slightly indicated wish! Ah, it was indeed a scene to gladden the heart of the father of one of them!
Eleeta's beauty, the sweetness of her disposition, and most charming and lovable ways endeared her so to me that I did not wonder Merna found them so attractive and satisfying; and my most fervent aspirations ascended for their happiness, both now and in the future.
With the Martians there is no false modesty about their courtships; all is natural, proper, and dignified; every one may see and every one enters into the true spirit of the thing. Mere flirtations, such as we are so familiar with, are quite unknown, as they would be contrary to all the natural instincts of the people. Everything upon Mars is honest, true, and straightforward--open and above-board. This must necessarily be so, in consequence of the Martians' powers of intuition, for any attempt at imposition or deceit would at once be detected.
I had an illustration of this when I asked Merna, "How they dealt with their criminals?"
"We have none to deal with," he replied, "and you will understand why, when I tell you, that if any one committed a crime, however small, and it was desired to find out the offender, it would be impossible to escape detection. He might fly to the other side of our world, but the intuitions of our experts would at once make them aware of his hiding-place; besides, he could not conceal what was on his mind from any one with whom he associated.
"In the earlier times when only a small proportion of the Martians were endowed with these powers to any large extent, there were occasional crimes; but as they were always detected, crime soon ceased to exist.
"Thus you will see that, quite apart from their high standard of morality, the Martians soon found that crime was a folly."
* * * * *
There was another love affair apparently developing which did not afford me so much satisfaction as that to which I have just alluded.
I noticed that John and Siloni were very frequently together; and, whatever might be the case with the latter, I had very little doubt that John was smitten with his companion's charms. It was, perhaps, nothing
to be wondered at, for Siloni was indeed a very nice girl, with beautiful features, dark hair, and dark eyes; whilst John was well-built, fully six feet in height, with black hair and moustache, and very good-looking; altogether a fine and attractive man, and it had often been a matter of surprise to me that he had never married.
Still, such a complication as this had never entered my mind when I came to Mars, and I was rather perplexed to know how best to deal with the situation. However, I thought it would be well to wait a little while and see how the matter shaped itself before taking any action.
CHAPTER XXII
CELESTIAL PHENOMENA SEEN FROM MARS--M'ALLISTER RECEIVES A PRACTICAL LESSON IN GRAVITATION
Mars is really an ideal world for an astronomer to live in, its skies being so clear, the air so thin and pure, and the stars shining so brilliantly.
Besides these advantages, the rapid movements of the two satellites of the planet result in a constant succession of celestial phenomena which afford very frequent opportunities for most interesting observations. Changes in the phases of the two moons, eclipses, occultations, transits, &c., are constantly occurring, so there is nearly always something to attract our attention to the Martian sky.
We have already seen several of these phenomena, and I will now describe what we have observed.
Early one evening when we were out with Merna, we looked up at the sky and saw the two moons a considerable distance apart, but approaching each other from opposite directions, Phobos appearing to move very rapidly. Both were near the full phase, Deimos being more nearly full than Phobos; and we watched them drawing closer and closer together till Phobos passed right in front of Deimos so as to hide it entirely. This is termed an occultation; and both the satellites had become full when the occultation occurred; but when they were again clear of each other both were beginning to wane.
This sight may be seen anywhere near the Martian equator about every ten hours.
The movements of Phobos seemed very peculiar to us who had lived upon the earth and seen all the celestial bodies appearing to move in the same direction.
I have already alluded to the fact that Phobos is only 3700 miles above the surface of Mars, and moves so rapidly that it makes more than three complete revolutions round the planet whilst the latter is turning only once on its axis.
The effect of this very rapid revolution of the satellite, which has no counterpart, so far as we know, in our Solar system is that, instead of rising in the east and setting in the west as all the other heavenly bodies appear to do, Phobos appears to rise in the west, cross the sky, and set in the east.
The moon and planets all actually move from west to east; the apparent reverse of this being caused by the more rapid movement of the earth on its axis, giving the other bodies the appearance of moving from east to west. If, however, our moon is closely watched, and its position with regard to a fixed star carefully noted, it will be found that in the course of a short time its real movement has been eastward, and that its position with regard to the fixed star has changed, although the revolution of the earth has appeared to carry both westward.
Phobos is 36 miles in diameter. Its actual period of revolution round the planet is 7 hours and 39 minutes, but, owing to the movement of Mars on its axis in the same direction, it appears to take a few minutes over 11 hours to complete one revolution.
Near the equator, Phobos is seen above the horizon for about 4-1/4 hours, and is below it about 6-3/4 hours. According as the place from which it is viewed is farther from the equator so will the time of visibility of Phobos be decreased, until when latitude 69° is reached in either hemisphere, it will cease to become visible at all. This is owing to its nearness to the planet; and, Mars being small, the curve of its sphere is sharp, so that the horizon is more limited than on the earth, and the satellite is shut out from view anywhere above latitude 69° by the body of the planet.
Another peculiarity is that, when in the zenith, Phobos appears twice as large in area as it does when near the horizon, and notwithstanding its very small size, Phobos appears rather larger than our moon, because it is so near to the planet.
The length of the Martian "night" is about 12 hours and 20 minutes, and during this very short time Phobos may be seen to rise in the west, set in the east, and rise again once more in the west. Consequently it will be evident that it must travel very rapidly across the sky. It really moves over a space of 32-1/2° in a single hour--a great contrast to the slow and stately movement of our moon, which only passes over half a degree in an hour.
Moreover, Phobos may be seen to rise as a new moon, pass through its phases to the full, wane, and again become new, all in the course of a single Martian night; or it may be seen twice full and once new during the same time.
Even this does not exhaust the list of phenomena, for, being so close to Mars, Phobos is very frequently eclipsed by the shadow of the planet. On the other hand, the sun may be eclipsed by Phobos something like fourteen hundred times in the course of a Martian year; and, as already mentioned, the other satellite is often occulted by Phobos--sometimes when both may be only at the half full phase, and these occultations look very peculiar.
Deimos, being only 10 miles in diameter and about 12,500 miles from the surface of the planet, does not give rise to so many phenomena as the nearer satellite: still they are very numerous.
It revolves round the planet in 30-1/4 hours, but appears to take 131-1/2 hours to do so, being above the horizon about 60 hours, and below it nearly 72 hours. These are the times as seen from the equator; but, as in the case of Phobos, the farther the place is from the equator the shorter is the period that Deimos is seen above the horizon, until, when latitude 82° is reached in either hemisphere, it ceases to become visible at all.
Our moon, being so very much more distant from our earth, could be seen from both the poles.
Deimos also passes nearly twice through all its phases whilst it is above the horizon, viz. during about 60 hours, and may be seen twice full and twice new in that time.
Eclipses of Deimos by the planet and occultations of it by the other satellite are very frequent. Being so small, it can never cause an eclipse of the sun, but it transits the sun as a dark spot about one hundred and twenty times during the Martian year.
This is really a very inadequate list of the phenomena connected with the satellites, but it will be seen that the number is enormous compared with the few eclipses of the sun or moon seen on the earth during the course of one year. Certainly Mars is an astronomer's world!
Merna heard my statements respecting these movements and phenomena as I explained them to my two friends; and when I had finished, he remarked, "You seem to be fairly well posted in these matters, sir?"
"Yes," I said; "thanks to our astronomers, both professional and amateur, all these things have been very carefully calculated; and, with the exception of a few doubtful points, we probably know nearly as much about them as the Martians themselves do."
M'Allister then turned to me and said, "Professor, you told us that the two satellites of Mars revolved round the planet in a certain time, but in each case you afterwards said they appeared to take a much longer time to do so. I'm rather puzzled to understand how that can be."
"It's really a simple matter, M'Allister," I answered, "and I think I can make it clear to you. While the satellite is making one revolution round the planet the latter is turning on its axis in the same direction as the satellite is moving, following it up in fact; and you will I think understand that in these circumstances the people on that part of the planet where the moon is visible must necessarily keep it in view for a longer period than would be the case if the planet were not revolving in the same direction.
"You have been used to being on board a ship; so suppose your vessel was steaming twelve miles an hour and there was another vessel at anchor just twelve miles ahead of you, you would reach it in just one hour, would you not?"
"Yes, certainly I should," replied M'Allister.<
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"Now," I continued, "suppose that the other vessel, instead of being at rest, was moving away from you at the rate of six miles an hour; after you had steamed one hour it would still be six miles ahead of you, and it would take you exactly another hour to catch it up. So you would be just double the time reaching it when moving as compared with the time required to do so when it was at anchor. This is very similar to the cases of the satellites of Mars, and much the same thing happens in regard to Mars and the earth. If they are opposite to each other at a certain point, Mars will have taken much more than one revolution round its orbit before they will be opposite to each other again, because they are both moving in the same direction. Do you see it now?" I asked.
"Yes, Professor," he replied. "I know now, because you have cleared it all up. It's simple enough when one understands it."
Merna then asked me if I would like to see some of their astronomical instruments, and, on my replying that I should very much like to do so, he took us to an observatory where Corontus was at work.
I was at once struck by the small size of the telescopes; and, on inquiring about them, Corontus told me that very large instruments had long become obsolete, for these small ones could be used for all the purposes for which a large one had been required, and gave better results.
I examined one of them and found, to my surprise, that it embodied the very ideas that I had long been trying to carry into effect. With this view I had made many experiments, as it seemed to me that it ought to be possible to construct an instrument of moderate and convenient dimensions which would show as much as our monsters will show, and yet be capable of being used with low powers when occasion required. I had endeavoured to attain this result by the aid of electricity, but failed to do so. Evidently I had missed something, but here was the thing itself in successful working, as I found upon testing it.
On looking at some drawings of Saturn, which were hanging up in the observatory, I noticed that this planet was depicted with two faint outer rings which do not appear on our drawings of the planet. One of these rings has, however, been discovered by M. Jarry-Desloges, but the outermost ring is still unknown to our observers. This ring is a very broad one, its particles being widely scattered, hence its extreme faintness.
