Invited_talk abstract details

The great luminous arch of the night that often seems to join opposite regions of the horizon has always
impressed the imagination of the people used to address their eyes to the sky. In the western civilization it is
named Milky Way since it was believed to be produced by the divine milk sprung from the breast of Juno
while nourishing Herculis. Nordic people believed that the Milky Way was a track followed by birds toward the southern regions. In a vast area from North Africa to Armenia the faint nebulous light is formed
by straw left out from a carriage. In the middle ages the Milky Way has been mysteriously named Daemon Meridianus,
while often it has been considered the way followed by the souls after that.
In the eighteenth century it has been realized that the phenomenon is due to the fact that we are within a flat disk and we look
along the principal plane, where the stars are much more numerous than in the other directions. Since then the study of our
stellar system, named also Milky Way, has been thoroughly investigated in all the details and in all the wavelength range.
The latest result being a deep modification of the previously supposed structure of its spiral arms.