Arachne

To the best of my knowledge there are twelve mythical signs of the zodiac plus a 13th hypothetical one; Arachne.

My understanding of the signs of the zodiac is that they are constellations of stars through which the sun passes over the course of the year. As far as I am aware there is no constellation called Arachne and so the sun does not pass through one.

It tickles me that one of the hypotheses claims that the sign of Arachne straddles the cusp of Taurus and Gemini but what tickled me more was finding Arachne within her constellation on my bathroom ceiling.