Having laid out Hipparchus’ alignment, Ptolemy offers several of his own
in order to provide those who come after us with a means of comparison.
Stars in Aries. The two northernmost [α and β Ari] of the three stars in the head of Aries [α, β, and γ Ari] and the bright star in the southern knee of Perseus [ε Per] and the star called Capella [α Aur] lie on a straight line.
[Stars in Taurus.] The line drawn through the star Capella [α Aur] and the bright star in the Hyades [α Tau] cuts off the star in the advance leg of Auriga [ι Aur] a little to the east. Also, the star called Capella [α Aur], the star which is common to the rearmost foot of Auriga and the tip of the northern horn of Taurus [β Tau], and the star in the advance shoulder of Orion [γ Ori] lie on a straight line.
[Stars in Gemini.] Furthermore, the [two] bright stars in the heads of Gemini [α and β Gem] and the bright star in the neck of Hydra [θ Hya] lie very nearly on a straight line.
[Stars in Cancer.] Furthermore, the two stars close together in the front leg of Ursa Major [ι and κ UMa], the star on the tip of the northern claw of Cancer [ι Cnc], and the northernmost of the [two] ‘Aselli’1 [γ Cnc] lie on a straight line. Similarly, the southern Asellus [δ Cnc], the bright star Procyon [α CMi], and the bright star between them (which is advance of the head of Hydra) [β Cnc], lie almost on a straight line.
[Stars in Leo.] Furthermore, the straight line drawn from the midmost star [γ Leo] of the [three] bright stars in the neck of Leo [ζ, γ, and η Leo] to the bright star in Hydra [α Hya] cuts off the star on the heart of Leo [α Leo] a little to the east. The [line] from the bright star in the rump of Leo [δ Leo] to the bright star [γ UMa] in the back thigh of Ursa Major (which is the southernmost star on the rear side of the quadrilateral), cuts off, a little to the west, the two stars which are close together in the rear paw of Ursa Major [ν and ξ UMa].
[Stars in Virgo.] Furthermore, the line from the star in the back of the thigh of Virgo [ζ Vir] to the second star from the tip of Hydra’s tail [γ Hya]cuts off the star called Spica [α Vir] a little to the west. The line from Spica to the star in the head of Bootes [β Boo] cuts off Arcturus [α Boo] a little to the east. Spica and the [two] stars on the wings of Corvus [δ and γ Crv] lie on a straight line. Spica, the star in the back of Virgo’s thigh [ζ Vir], and the northernmost, bright star [η Boo] of the three in the advance knee of Bootes [η, τ, and ν Boo] lie on a straight line.
[Stars in Libra.] Furthermore, the [two] bright stars in the claws [α and β Lib] and the star on the tip of Hydra’s tail [π Hya] are very nearly on a straight line. The bright star in the southern claw [α Lib], Arcturus [α Boo], and the midmost [ζ UMa] of the three stars in the tail of Ursa Major [ε, ζ, and η UMa] lie on a straight line. The bright star in the back of the thigh of Ursa Major [γ UMa] lie on a straight line.
[Stars in Scorpius.] Furthermore, the star on the rear shin of Ophiuchus [ξ Oph], the star in the fifth tail-joint of Scorpius [θ Sco], and the more advanced [ν Sco] of the two stars close together in its sting [λ and ν Sco] lie on a straight line. The most advanced [σ Sco] of the three stars in the breast of Scorpius [σ, α, and τ Sco], and the two stars in the knees of Ophiuchus [η and ζ Oph], form an isoceles triangle, the apex of which is the most advanced of the three stars int he breast [σ Sco].
[Stars in Sagittarius.] Furthermore, the star on the front, southern hock of Sagittarius (which is of second magnitude) [β Sgr], the star on the arrow-head [γ Sgr], and the star in the rear knee of Ophiuchus [η Oph] lie on a straight line. The star [α Sgr] in the knee of the same [front] leg of Sagittarius (which lies near Corona [Australis]), the star on the arrow-head [γ Sgr], and the star in the advance knee of Ophiuchus [ζ Oph] lie on a straight line.
[Stars in Capricorn.] Furthermore, the line drawn from the bright star in Lyra [α Lyr] to the stars in the horns of Capricorn [α, β, ν, and ξ Cap] cuts off the bright star in Aquila [α Aql] a little to the east. The line from the bright star in Aquila to the first-magnitude star int he mouth of Piscis Austrinus [α PsA] bisects, approximately, the interval between the two bright stars on the tail of Capricorn [γ and δ Cap].
[Stars in Aquarius.] Furthermore, the line from the first-magnitude star in the mouth of Piscis Austrinus [α PsA] to the star in the muzzle of Pegasus [ε Peg] cuts off the bright star in the rear shoulder of Aquarius [α Aqr], a little to the east.
[Stars in Pisces.] Furthermore, the stars in the mouths of Piscis Austrinus [α PsA] and the southern fish [of Pisces] [β Psc] and the [two] advance stars of the quadrilateral in Pegasus [α and β Peg] lie on a straight line.
While the above alignments were all ones first reported by Ptolemy, he does note that he was able to check them in a limited extent against observations from Hipparchus because a
globe resulting from the observations made [in Hipparchus’ time]
was available to Ptolemy, presumably at the Musaeum of Alexandria2. Using this, he found that these alignments matched Hipparchus’ celestial globe quite well further strengthening his argument that the stars did not appear to change positions.
