Jay Taylorian (born Jay Taylor on 17th September 2009) is the youngest of the brothers of Cometan and is referred to in the context of Astronism by his religious mononym of Sideron.

Born in Royal Preston Hospital in Preston, Lancashire on 17th September 2009 to Nadine Lathrope and Sean Taylor, Jay is the youngest of Cometan’s brothers. Described as deeply caring and very clever, Jay and Cometan share a close bond with one another. Jay's religious mononym, Sideron, is derived from the prefix sidero- which means in relation to stars and constellations, thus pertaining to theme of Astronism, the religion which Jay was prophesied to make contributions to.

Jay currently attends St Mary’s Roman Catholic Primary School Leyland from 2013 and will soon go on to attend St Mary’s Catholic High School in Leyland from September 2021. Unlike his older brother Kieran, Jay never received his First Holy Communion and is therefore not Roman Catholic, which demonstrates the waning influence of his grandmother, Irene Mary Taylor and her staunch adherence to Roman Catholicism, insistent that her grandchildren all receive their holy communion. Timeline September 17, 2009: Jay is born Jay Taylor in Royal Preston Hospital in Preston, Lancashire. (Fun fact: Jay shares the same birthday as Cometan’s aunt, Karen Elizabeth Warbrick).