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28 - stellations are. made, ric. 40. Of course there are hundreds of other stars in these constellations "that: we do not see, as astronomers "use telescopes and form the constel- lations to take in the many stars 'that' the ee shows grouped to- is a "The 'constellation of the Big Dip per looks something like a dipper 'Dait> is only..a part of a larger. con- - stellation called Ursa Major. . Now we don't need to bother our- My selves much about the constellations. "We can pick out the first magnitude 'stars without knowing anything about the: constellations if we wish. In order to locate almost any of our stars we must know the Big Dip- per when we see it. But nearly every- one knows just where to look for that. I re Fic. 41, It. never sets,- but travels cle around the north star every night. Get. some one to show you the Big Dipper and the start is made. "you Gant use any of the stars inithe dipper for azimuth work because there are no bearings given in the azimuth book for anything as far north as that. But the stars of the Big Dipper form ranges that can be used for lo- cating the othe . stars. The pie Dipper and the North Star (Polarisj. The two stars that form the' side of the bowl of the dipper form a range that always points directly at the North Star. The Big Dipper takes a daily whirl around the north star, as shown in Fig. 40. -manner in which several of our con- ing stick for the stars. are about 10 degrees. _ stars. nitude stars. im 4 Scit-)- But. therefore, -in the daytime. _ that - above THE MARINE REVIEW Of course, actually, the dipper does not change position, but the daily whirling of the earth makes it appear to change. You "will notice that no matter where the Dipper is the two stars that form | the outside of the . bowl always point to the north star. You should make a Little measur- The two stars of the dipper apart. Hold a stick at arm's length and cut notches that form the brim 'in it to correspond with those two . This will show you 10 degrees of the sky distance. es to show you grees. The North Star degrees from the Dipper.. A pictire of the Dipper as we. see it every night is shown in Fig. 41.. When you look for the Big Dipper you are just) as likely.to see -1t up- side down as any. other way. So don't expect to always see it as shown in Pig. 41. The stars that we will now attempt to find are named below. Their prop- er names will be the ones that we will use, but we also give 'their con- stellation names in order that you may better unde:stand the Nautical Almanac. Eleven of the brightest stars in the heavens. These can all be used for azimuth work: Arcturus (Bootes A). Spica (Virginis A). Aldebaran (Taurus A), Rigel (Orion B), Betelgérz (Orion A). Altair (Aquila A). Sirius (Canis Major A). Procyon (Canis Minor A). Pollux (Gemini A). _ Regulus (Léo A). Antares (Scorpio A). Astronomers call these first mag- First magnitude are the brightest stars, then come. second magnitude stars, etc. There are about 20 first: magnitude stars in the heav- ens but ,those given here are. the only ones that we have figures for in the azimuth book. All these stars cannot be. seen every night. They rise four minutes earlier each night and at certain times of the year, they pass over our heads The best time to identify a star is when it is rising or just after it has risen: It is more nearly alone then .as the atmosphere near the horizon obliterates. the multitudes of small. stars. that are plainly visible higher up in the. sky. Those stars rise exactly -in the east are the horizon about 12 Those stars that rise and set away above it. Cut more notch- . 10,20. and 30 de= is nearly 30 | remain the .other | and for hours, horizon below -- the 12 hours, to the southward of us spend a longer time, below the horizon than they do And those toward the northward of us spend a longer time above the horizon than below jit, Some (as in the. case .68 tie Big | Dipper) never set at all. The North Star never changes its position in the sky. It is at the north pole of the heavens. We have prepared a "table giving the time of rising and setting and the meridian passage of these 11 stars for the first day of each month. Ag a star rises four minutes earlier each night you can easily figure the time of rising and setting for the particu- lar night you wish. The time of rising given is the sun time of the locality that you are in. But you must not expect these stars to appear just at the minute given as there are different conditions that will affect these calculations. Fifteen minutes should be allowed ether way. <A: star wil rise earlier the farther north you get so our ta- ble is made for latitude 45--which should make a good average time for rising all over the lakes. <A star passes the meridian by sun time the same the world over. If the Nautical Almanac tells you that a star passes the meridian at Greenwich, Eng., at 8 p. m., then it will pass your merid- jan at 8 p. me: If a. star passes ae meridian at Cleveland at 8 p, m.,, it will pass the meridian at Duluth at 8 p: m. Of course Cleve'and sun time is not the same as Duluth sun time. The Nautical Almanac would mean 8 p. m. by Greenwich time while the star passes your meridian at 8 p. m. by your time. Taking the stars in the order given in our list we will locate Arcturus first. Arcturus. Find the Big Dipper. Follow the curve of the handle arcund for 30 degrees and you find Arcturus--thus. See Fig. 42. - eR a ce . oR ~ os eo Kec TURUS i ' * 7 ae FIG. 42. Spica, Find Arcturus as shown above and follow the same circle around for