The Bridgeport evening farmer., 1915-10-01

EOGE FTa Z2 rSa.
 LAST Qrto 50 tn. -@'
 Position and Phase of haoon shown for
 Dominating the heavens on moon less nights throughout the month of October will be found the greatest of planets, Jupiter. Our map shows his
 place in the sky at g o'clock on the fourth, but his position will vary only slightly the whole month. and he should be recognized without diff culty. He shines without twinkling, and s.his bri1liancy in stellar magni- tude is about minus two and a half,
 thus being far brighter than the brightest of the fixed stars, Sirius, of magnitude minus one and ha1f.' Jupiter is Six times as brilliant Vega, the beautiful 3blue-waite star of the constellation Lyra glowing little to- the west of the zenith. The most striking and fundamental diff ference, however. between the planet and the star comes out upon the use of small telephone or good opera or field glass. The star changes not at all in appearance-nay seem lit- the brighter, perhaps-but the planet now shows us a definite disk. The observer of Jupiter will see not only the planetary disk itself, but also small bright spots, tiny disks them selves, which are his satellites, or moons. There are five such moons l belonging to him, but one is only 1 visible Sin the most powerful tele- 1 scopes, while the other four are cas- | fly seen with even an opera glass. lThe number visible to us at any one | instant will of course depend o1i the positions which the satellites may be holding in their respective orbits around their parent body at that mo-
 ment.
 Measurements of Jupiter.
 Jupiter is the largest planet of the solar system and it's diameter is about 88, ,0O0 miles, a little, more than II times that of the earth. The surface area is 122 times as great as that of the earth and the bulk is 1855 times greater than earth's The density of the substance making up the planet is, however much less than that of the earth-in fact, less than a quar- ter, so that in spite of it's enormous size, the planet Jupiter is only 317' times as heavy as our own planet
 Surface Conditions on Jupiter. There can be no doubt that Jupiter has not yet reached the stage of cool ness attained by the earth / Continu- ous changes in the appearance of it's surface, the steady manufacture and dissipation of cIoud-ike bodies cer- tainly indicate to state far from
 equilibriu and point to rapid and violent circulation of matter ~in the planets body. Furthermore, owing l to the distance of Jupiter from the sun, we are sure that the sun cannot be supplying the necessary. heat for these, phenomena, and we are forced to the conclusion that Jupiter is very hot from it's own energy. It must be that Jupiter in a very small way is acting like the sun and producing heat energy by condensation of the outer particles Yet also are we sure that this cannot be going on with 7aiA 0 he TaI0 of1 self Luminous. However, one thing may be written down with all cer- tainty: Jupiter is in state at pres ent to sustain life as we know it on this planet.
 The Satellites.
 Nc record of knowledge of Jupi-. ters moons is found in Greek as- tronomy, as it seems to be just impos- sible to see them with the naked eye though some people have claimed to, see them thus. Most likely the first human being to see them was Calico. to whom the credit for their discov- cry has always been given. In 161O> he studied Jupiter with his newly in vented telescope and found no difi- culty in recognizing that these tiny spots of light seemed to follow along with Jupiter in his course through the heavens and at the same time ap- bearing now one side of him and now on the other. To us it seems irn- possible to give any other interpfe- tation to this observation than that these bodies must be revolving around Jupiter. Calico so interpre- tated it, and this discovery aided him much in his support of the Coperni- can system. The fifth satellite re- mained undiscovered till 1892, when Professor Barnard at the Lick Ob- servatory in California found it with
 his high powered telescope.
 The courses, orbits or "ephem- erides'' of the four older moons of Jupiter have been studied with great care ever since their discovery and long ago were already so we'll known that predictions could be made with greatest certainty of their positions and their eclipses Aby their mother planet. One astronomer, however, noticed that thesel ecHpses seemed always to occure a little ahead of time when the earth was moving in it's orbit around the sun in such a way as to approach Jupiter and falling just 8. little behind the computed time
 when tn eearth was moving in such a way as to recede from the great planet. This observer, Roemer by name, suggested that this difference was due to the time taken by light to travel through the intervening space. By using the retardation time .7f af