"There are possibilities of life on some of our brother worlds, though that is not in any way a necessity, possibly on Mars and probably on Venus, with Mercury very doubtful but more probably lifeless. The moon we will not consider, for we believe that it is dead long ago--even if it ever had any form of life upon it. It may even be that some world of our solar system has ceased to bear life and it has been suggested that possibly Mars is such a world. This is in no wise unreasonable. It is entirely probable that some of them are not in a life-bearing condition, just as a tree in your orchard may not have obtained maturity yet. Their heyday is yet to come, perhaps this will be when the earth and all its present life are cold and dead--dead of old age! for a world must die just as a man must die." Jupiter, Saturn, Uranus and Neptune are considered, he says, to be worlds of the future, their low density and other considerations leaving little doubt of their unripeness for life. Perhaps millions of years will pass before these giant worlds are in a condition to welcome life of any description. Many astronomers believe that the conditions for life such as we know it on earth, are more likely to be found on Venus than on any other planet; others think that Mars, being evolutionally older, may have even passed the stage in which we now find ourselves, or that it may have developed, to suit the conditions on Mars, along quite a different line. Life adapts itself to many extremes, it may live in intense heat and freezing cold, in the air, in the water and under the ground. Speculation on this subject has disclosed the most interesting data, but as yet we do not know, and may never know, if there is life on any of the planets. THE GIANT PLANET OF JUPITER, THE KING OF THE GODS _Diameter--88,300 miles_ Jupiter is the largest planet in our solar system. With high magnifying power it is seen to be a great "orange-shaped" globe, larger than the full moon to the unaided eye, with a bulging equator and flattened poles. This polar depression is ¹⁄₁₆th of its diameter causing the polar diameter of 84,400 miles to be several thousand miles less than its equatorial diameter, which is 90,200 miles. This colossal world is favorably situated for observation three months out of every year, traveling eastward along the zodiac, and spending around twelve months in each zodiacal constellation. It requires twelve of our years for Jupiter to complete a revolution around the sun.