Venus has the same phases that Mercury has. She shows her full face when at superior conjunction, and is then farthest away and smallest to our view. As she moves toward us she first becomes gibbous, and then, at eastern elongation, like a half-moon. As she comes nearer to inferior conjunction, and hence nearer to us, she becomes a thinner and thinner crescent, and as she goes from inferior to superior conjunction these phases are repeated in reverse order. We see less than half of her face when she is at her greatest brilliancy, a phase which usually occurs when she is about forty degrees from the sun, as she is a few weeks before and after inferior conjunction. A very small glass will show the phases of Venus. They have occasionally been seen without artificial aid to vision by an exceptionally good eye. They were not known, however, until they were discovered by Galileo after the invention of the telescope in 1610. Venus would be many times brighter than she ever appears if the entire disc of the planet could be seen when it is nearest to us. The apparent diameter of the disc at that time is nearly seven times larger than when we see it at the planet’s greatest distance from us. When Venus is in superior conjunction and farthest from the earth the disc measures only ten seconds, while at inferior conjunction its measure is nearly sixty-seven seconds. The diameter of the moon is about 1,868 seconds, so one could string across the diameter of the moon one hundred and eighty-six such planets as Venus appears to be when at her smallest, and only twenty-seven of the size that she appears to be when at her largest. Between these two extremes of size she changes gradually, day by day, from large to small and small to large, in ceaseless succession, as she approaches the earth and recedes from it in her orbital journey. Apparent diameter is determined by an actual measurement of the disc of a planet, and in the case of Venus indicates nothing as to brightness. When the apparent diameter is largest she is not visible to the naked eye. [Illustration: THE LOVELY CRESCENT THAT VENUS SHOWS WHEN TO OUR VIEW SHE IS AT HER GREATEST BRILLIANCY This remarkable photograph was made at the Yerkes Observatory by E. E. Barnard.] [Illustration: RELATIVE APPARENT SIZE OF VENUS AT DIFFERENT PHASES OF ILLUMINATION She shows the full disc when farthest away. As she draws nearer she shows first the half moon and then the smaller crescent. She is nearest when she shows the larger crescent. She is brightest, though, when she shows the smaller crescent.] VENUS’S LIKENESS TO THE EARTH