Spiral Galaxies as Enantiomers: Chirality, an Underlying Feature in   Chemistry and Astrophysics
  Spiral galaxies are axi-symmetric objects showing 2D-chirality when projected onto a plane. Features in common with tetrahedral molecules are pointed out, in particular the existence of a preferred chiral modality for genetic galaxies as in aminoacids and sugars. Environmental effects can influence the intrinsic chirality of originally isolated stellar systems so that a progressive loss of chirality is recognised in the Hubble morphological sequence of galaxies. 
Salvatore Capozziello, Alessandra Lattanzi