The Birmingham age-herald., 1921-07-03
THE STARRY SKIES IN JULY
By PROFESSOR BARTON


 If we continue the arc formed by the stars in the handle of the Big Dipper in Ursa Major we follow a stream of stars in Bootes to the bril- liant red star Arcturus at A. A fur ther extension of the same arc leads us to another bright star. Spica of Virgo, at E. Some months ago actual measurement showed that the di- ameter of Betelgeux for Alpha oricn- is was 800, 900, 900 miles. The secoad application of the same method was to the star Arcturus, which was sup posed to be the second largest star but much smaller than Betelgeux. The result showed that Arcturus was l9,000000 miles in diameter and it's volume roughly 11,000 times that of the sun. As these results were much more difficult to obtain than those upon Betelgeux. the achievement is more remarkable. They indicate. however, that there are but few stars whose diameters are large enough to be found by these methods.
 If wo draw a line from north to south on our map, we find that it passes through the serpent constol lations. Lowest in the south is the well-marked constellation Scorpio (the Scorpion). with it's bright red dish star Antares. Next above this is Ophiuchus (the serpent holder), and Serpens, the serpent which he is holding. In this case, we have one constellation crossing another. Just south of the zenith Is Hercules the Kneeler, upside down as we see him, with his head toward the head of Opbiuchus and his foot resting on the head of Draco the Dragon. Her cules holds branch in his left hand in which serpents are entwined. Dra- co Is one of the circumpolar constel- lations which may be seen nearly at all times, but is in it's best position this month. It will be seen to make semi-circle about the Little Dipper, Ursa Minor, and then turn and end in diamond-shaped head just north of Hercules. This arrangement of men and serpents can scarcely be ac- cidental. No theory as to the req son for the arrangement Is we'll es- tablished. Attempts have been made to trace the story of the Garden of Eden in these constellations.
 The Planets
 The position of Jupiter and Sat urn are marked on the map This is the last month in which they may be seen well. Venus is brilliant morn- ing star. It is at it's greatest west ern elongation July 1. It may be seen in the east before sunrise. Mer- cury Is similarly at it's greatest west ern clongation July 2s. On July f. the earth is at the point of it's orbit farthest from the sun. At this time the earth Is about 3.0o0,000 miles further from the sun than in Janu- ary. In order to show the nature of the earth's motion the orbit of the fe ellipse, In which the flattening is much exaggerated. The real orbit of the earth Is So nearly true cir cle that if accurately represented in figure very minute examination would be necessary to show the de- parture from true circle. The boundary of the map in Figure 1 is true circle. If the earth's orbit were represented by this circle the representation would be accurate to about one-thousandth of an inch.
 The moon In It's path among the stars always hides the stars behind it. At times 1t passes between us and some of the brighter stars-oc- cults them as astronomers term it. Two such occulations occur this month. On July 1s, Rho Sagitarrii disappears behind the moon at 3:l1 &. m., as seen from Washington, and at nearly that time elsewhere. It remains hidden Al minutes. On July 30, Delta Tauri is similarly occult ed This occulation begins at 4:0S a. m, and lasts 70 minutes.
 Do the Stars Movef
 Do the stars move? Whatever is meant by the question, the answer is yes. Our map (figure D shows the positions of the stars at D. m. July fnp lot f.11 nf Change any oe these factors and the appearance of the sky will be diff ferent. The earth rotates on It's axis, carrying the observer with 1t, once in : a day; hence everything not on the earth will appear to move in the op- posite direction, just as the scenery appearS to move when riding in a trasn. For this reason the stars ap- pear to rotate from east to west as though fixed on great sphere whose axis is that of the earth. This axis of rotation of the sky Is now near the north star. For this reason the stai3 are not in the same position at different times of the night. Then, too, the earth moves about tho sun. As the direction of the sun changes, due to the earth's revolution about it, so does the direction opposite to the sun change, and his is the direction in which we see stars-that is, at night. Hence as we arc looking in different direction at night at diff ferent times of the year we see diff serent stars For this reason the stars we see at D. m. July are not 4 the samc as those we see at the same time August 1. On August 1 at o'clock they will be in the same po- sition as they were at g p. m. July l. for in month the earth has nov Sd one-twelfth of the way around in it's orbit, month being one e-twelfth of year and one-twelfth of 24 hours,