From observations of the motions of over 20 000 local stars (within 300 parsecs), and using numerical simulation, Charles Francis and Erik Anderson have shown that, contrary to conventional wisdom, stars tend to move along a spiral arm during the inward part of their orbits, leaving the arm shortly after pericentre crossing the other arm on the outward part of the orbit and rejoining the original arm shortly before apocentre.
In the main core of Chironico, with its typical block buildings, is the small church of S. Ambrogio with a medieval twin apsis and remarkable frescoes.