Cygnus (Cygnus); the eastern arm of the cross points to Enif, the western arm to Eltanin, and the lower right angles point to Altair and Vega. Altair is identified by the small stars on either side of it, sometimes called the guardians. This configuration is unique and should identify Altair through a break in the overcast with no other stars showing. Vega may be identified under these conditions by an almost perfect parallelogram slightly to the south and east of it. These are fourth magnitude stars and are not too distinct if the weather conditions are unfavorable.
Corona Borealis The northern crown (Corona Borealis) is a group of stars shaped like a bowl about two thirds of the distance from Vega toward Arcturus. This constellation forms a distinctive pattern and connects the dipper group to the northern cross to the east. Second-magnitude Alphecca in this group is sometimes used by navigators.
Rasalhague forms nearly an equal triangle with Vega and Altair. This second-magnitude star and third-magnitude Sabik, to the south, are occasionally used by navigators.
The autumn sky is marked by an absence of first-magnitude stars. The northern cross has moved to a position low in the western sky, and Cassiopeia is on the meridian to the north. A little south of the zenith for most observers in the United States the great square of Pegasus (the winged horse) appears nearly on the meridian. The eastern side of this square, and Caph in Cassiopeia, nearly mark the hour circle of the vernal equinox. Alpheratz and Markab, second-magnitude stars at opposite corners of the square, are the principal navigational stars of this constellation. Second-magnitude Enif is occasionally used.
The square of Pegasus is useful in locating several navigational stars. The line joining the stars of the eastern side of the square, if continued southward, leads close to second-magnitude Diphda in Cetus (the sea monster). Similarly, a line joining the stars of the western side of the square, if continued southward, leads close to first-magnitude Fomalhaut. A line through the center of the square, if continued eastward, leads close to second-magnitude Hamal, in Aries (the ram). A curved line from Alpheratz through Andromeda leads to Perseus. The only navigational star used in Perseus is the second magnitude Mirfax.
The navigational stars associated with Pegasus are Alpheratz, Markab, Diphda, Fomalhaut, and Hamal. Capella, rising in the east as Pegasus is overhead, connects this group to the Orion group while Enif acts as a link to the west.
The winter sky is great but for taking sights but cloudy conditions make it hard sometimes.No other part of the sky contains so many bright stars. The principal constellation of this region is Orion (the hunter), probably the best-known constellation in the entire sky, with the exception of the big dipper. This is well known to observers in both northern and southern hemispheres, as the belt of Orion lies almost exactly on the celestial equator. Rigel and first-magnitude Betelgeuse lie approximately equal distances below and above the belt.
Several good navigational stars can be found by the use of Orion. If the line of the belt is continued to the westward, it leads near first magnitude, Aldebaran (the "follower", so named because it follows the" seven sisters" of Pleiades), in the V-shaped head of Taurus (the bull). If the line of the belt is followed in the opposite direction, it leads almost to Sirius, the brightest of all the stars. This is the principal star in the constellation of Canis Major, the hunter's large dog. Starting with Sirius, a rough circle can be drawn through Procyon in Canis Minor (the little dog), Pollux and Castor in Gemini (the twins), Capella in Auriga (the charioteer), Aldebaran, Rigel, and back to Sirius. All of these except Castor are first-magnitude stars.
Several second-magnitude stars in the general area of Orion are bright enough for navigational sights, but are seldom used because there are so many first-magnitude stars nearby. Four of these second-magnitude stars are listed among the principal navigational stars of the almanac. These are Bellatrix, just west of Betelgeuse; Alnilam, the middle star (actually, a spiral nebulae) in the belt; Elnath, in Taurus; and Adhara, part of a triangle in Canis Major, and just south of Sirius.
On the meridian far to the south the brilliant Canopus, second brightest star, is visible only to observers in the United States south of latitude 37 1/2°. This star is part of the constellation Carina (the keel).
The south polar region contains a number of bright stars, the person who travels to the southern hemisphere for the first time is likely to be disappointed by not seeing of any stars similar to those with which he is familiar. The famed southern cross (Crux) is great to look for when in southern latitudes. There is a false cross and can be mistaken for the southern cross. Canopus is another great star for taking sights and is due south of Sirius. In the south latitudes there very few navigational stars I like to try and get Achernar and Peacock when taking sights.
