ON THE PLANETS.

Clutha Leader, Volume XXXVIII, Issue 9, 4 August 1911, Page 2

ON THE PLANETS.

ARE THEY HABITABLE? INTERESTINcTcONJECTURES. This question has been asked so many times that some consideration will, be given to the subject. The quantity oi intensity of radiant energy received by the earth from the sun must of course be used as a basis of comparison, since the sun is in the source of all we have. The distance of the earth from the sun is 92,882,000 miles, and the heat and light received are familiar to everybody (writes Edgar Lucien Larken). Mercury. The planet Mercury is nearest of all to the sun, distant 35,964,000 miles. From the known laws of Nature and of heat and light intensity in relation to distance, astronomers are able to compute values. Thus Mercury receives 6657 times more intense radiation from the sun than does the earth. Water boils here at a temperature of 212 degrees Fahrenheit. Then water on Mercury, if it exists, is dissipated into super-heated steam. All life as it now exists on the earth would be destroyed, and if people living on Mercury have eyes like ours, they would instantly be made blind by the intense brilliancy. That is, if the atmosphere of that planet is like that surrounding the earth. It is the air of a planet that determines the kind and quantity of waves of energy received, retained and rejected. The air of the earth receives energy waves from the sun and assimilates them as we observe. If our air should change in this respect it might soon be hotter or cooler, brighter or darker. Mercury has an atmosphere surrounding it; but we do not know its nature; and we have no way of finding what waves of energy it receives and makes available and rejects. Thus the air on our sister planet may screen off the intense rays of waves and make the surface capable of being inhabited. It may, but astronomers do not know anything of either its atmosphere or condition of surface. Venus. This beautiful world, now the brilliant "evening star" (should be everting planet), is distant from the sun 67,185,000 miles; and, by applying the law, it is found that it receives 1.9335 times—almost double the intensity of radiating energy from the sun than the earth does. These days in summer on earth are hot; but to almost double the heat and light would be disastrous. Thus ffie heat now in the Middle West, ranging from 96 to 103 degrees, is almost unendurable, arfd has already taken many lives. But Venus has a deep atmosphere. I saw it as a ring of pearl at time of transit across the sun's disc on December 6, 1882. This envelope of vapor may so completely modify the intensity of solar energy that such creatures as we human beings are could exist there in health and strength. But the word may has to be used, because we do not know what the air of Venus is like, nor of other considerations. Mars, This ruddy and much-talked-of world is distant 141,535,000 miles from its source of supply—the sun; and by means of the magic laws, we know that the intensity of this supply is .4306 that received by the atmosphere of the earth. The air of Mars is rare; but we do not know whether it is composed of oxygen and nitrogen, as is the case with our air, nor do we know what other gases enter its composition nor the quantity of water vapor suspended. Again, it may be possible for life to exist there, but we do not know. The air would be obliged to select and use a large proportion of the waves received to support life of the kind here on the earth, since only two-fifths of the intensity are radiated out that far. Jupiter. This huge world, 1283 times larger than the earth, and distant 483,140,000 miles from the solar globe, receives .037, or about one-twenty-fifth the intensity of radiance,. But it must possess a vast quantity of air or gas, for dense streaks of what are supposed to be clouds are always visible in large telescopes. These are supposed to be clouds, as they change with a rapidity far too great for surface changes. Since we do not know of what this gaseous envelope is composed, none can say aught of its inhabitants. Saturn. This splendid world, now morning planet, is in a lonely region, 885,884,000 miles from its base of supply of energy, nine and one-half times

farther than the earth, and, therefore, receives one-eighty-first part of the energy undulations received here. It is surrounded by gas or vapor, supposed to be, for, it has changing outlines like clouds, but not nearly so pronounced as in the case of Jupiter. It is 762 times larger than the earth, but it is in density about like that of gasoline, less than that of water. Cut down the earth's supply of heat and light to one-eighty-first part, and it would be indeed cold and dark; no life as known to us could exist for a moment. Uranus and Neptune. Distant 1,781,680,000 and 2,789,831,000 miles respectively, are nineteea and thirty times more remote than the earth, and receive .0027 and .0011— one-three hundred and eighty-first and one-nine hundredth of the intensity of the energy; so it matters little what kind of atmosphere surrounds them, for if all energy received could be utilised, then the cold and darkness would be unbearable by any terrestrial form of life. The sun as seen from Neptune would appear but little larger than the planet Venus does to us. This view of planetary habitability can be presented in another light. Thus, suppose that the earth, precisely as it now is, could be placed where the other planets now are. Then, if moved toward the sun to the distance of Mercury, the ocean would be turned to steam; this would rise, form clouds and shut off radiation from the sun, and lower the temperature, but not low enough, no doubt, for the condensation into liquid again. AVe would be immersed in hot vapor. But another mighty factor must be included—gravitation. It would be 6.657 times more powerful, as well as heat and light. Huge tides in both air and ocean would rise and fall. Tides in the ocean would sweep over all low-lying shores. But the increased heat would develop powerful trade winds, and set up appalling hurricanes, typhoons and cyclones. And then the force of solar gravity would increase stresses and strains within the earth, resulting in terrific earthquakes. The earth at the distance of Venus would suffer all these things with an intensity of double, nearly, that now experienced. We could live on earth with double the heat and light, at north and south regions, but not at the torrid zone, unless watery vapor should screen of solar rediation. But doubled tides, winds and earthquakes would make our lives miserable. The earth at the distance of Mars would receive two-fifths of the radiant energy now received—.43o6 exact. But there would not be winds sufficient to prevent stagnation of air, nor tides to keep up a circulation of water. Evaporation, unlike that on Venus, would be so low that rivers would be far smaller and unimportant.