In Fig. 44 we show three views of Venus under different aspects. The planet is so much closer to the earth when the crescent is seen, that it appears to be part of a much larger circle than that made by Venus when more nearly full. This drawing shows the different aspects of the globe in their true relative proportions. It is very difficult to perceive distinctly any markings on the brilliantly lighted surface. Sometimes observers have seen spots or other features, and occasionally the pointed extremities of the horns have been irregular, as if to show that the surface of Venus is not smooth. Some observers report having seen white spots at the poles of Venus, in some degree resembling the more conspicuous features of the same character to be seen on Mars. [Illustration: Fig. 44.--Different Aspects of Venus in the Telescope.] As it is so very difficult to see any markings on Venus, we are hardly yet able to give a definite answer to the important question as to the period of rotation of this planet round its axis. Various observers during the last two hundred years have from very insufficient data concluded that Venus rotated in about twenty-three hours. Schiaparelli, of Milan, turned his attention to this planet in 1877 and noticed a dark shade and two bright spots, all situated not far from the southern end of the crescent. This most painstaking astronomer watched these markings for three months, and found that there was no change perceptible in the position which they occupied. This was particularly the case when he continued his watch for some consecutive hours. This fact seemed to show conclusively that Venus could not rotate in twenty-three hours nor in any other short period. Week after week the spots remained unaltered, until Schiaparelli felt convinced that his observations could only be reconciled with a period of rotation between six and nine months. He naturally concluded that the period was 225 days--that is to say, the period which Venus takes to complete one revolution round the sun; in other words, Venus always turns the same face to the sun. This remarkable result was confirmed by observations made at Nice; but it has been vigorously assailed by several observers, who maintain that their own drawings can only agree with a period about equal to that of the rotation of our own earth. Schiaparelli's result is, however, well supported by the letters of Mr. Lowell. He has published a number of drawings of Venus made with his 24-inch refractor, and he finds that the rotation is performed in the same time as the planet's orbital revolution, the axis of rotation being perpendicular to the plane of the orbit. The markings seen by Mr. Lowell were long and streaky, and they were always visible whenever his own atmospheric conditions were fairly good.