Page:The Music of the Spheres.djvu/266

 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.

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 th 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.

Even an opera-glass will give a view of Jupiter as a minute disk with two bands across its center and four luminous points on either side. These luminous points are satellites, three of which are larger than our moon and one almost as large. Jupiter has