In the latter half of the first chapter of the seventh book (VII.i) of his Mathematical Treatises, Ptolemy presents two sets of star alignments. First, a set of starlines set forth by Hipparchus some 260 years before Ptolemy’s, followed by a second set of Ptolemy’s devising. Two trips around the zodiac.
Here we proceed from the Crab to the Twins, following the Starlines of Hipparchus.
While most of these chapters can be read independently, we recommend beginning with the prologue and Chapter 1.
The header for Chapter 2 lists our favorite chapters.
A little bit of background on
Ptolemy’s Mathematical Treatises
Zodiac figures Crab and Leo
reach south to Hydra and Procyon
A line from tail of Lion to tail of Bear
helps mark what we call Berenice’s Hair
The first of two alignments based in Virgo
with triangles, and Arcturus, and . . . it’s complicated
These lines of Hipparchus are hard to parse
when viewing the stars of today
The Claws (or Libra) point the way
to Ophiuchus and the Snake
Stars in the body and tail of Scorpion
define surrounding constellations
The Archer / centaur wraps itself around
the stars which constitute the southern crown
The Water-Bearer’s urn? To solve this puzzle
We have to look up to the Horse’s muzzle
The bright stars of Pegasus serve to define
the southern of two Fishes joined by a line
The stellar Triangle, the maiden’s toes —
It’s scandalous where this alignment goes!
We start the shield by face of Bull
Orion brings account to full
A line drawn through the heads of the Twins
and Hipparchus ends where he begins