Zeus, his wife Hera and his son Herakles are at a tiny restaurant. Zeus wants Hera to feed Herakles as her milk makes everyone who drinks it immortal. Zeus wants this to happen so that he can protect his son.
Hera doesn't want to make her son immortal, but she doesn't know either that this is exactly what Zeus does want. So she is willing to feed Herakles her milk. Just when she starts feeding her son, she finds out that Zeus wants his son to become immortal.
Angrily she stands up and spills the milk she was supposed to give to Herakles. This leaves Zeus with no milk left and so Herakles cannot become immortal anymore.
The spilled milk looks exactly like the Milky Way in the galaxy, but Zeus and Hera don't notice this. They walk away arguing about what happened, leaving the spilled milk behind.
The waiter cleans the spilled milk not noticing the special shape... He doesn't know either this milk could make you immortal. What he, Zeus and Hera also don't know, is that Hera created the Milky Way by spilling her milk.
Hera is the Goddess of Marriage, Mothers and Families and many believe that she is the woman who created the Milky Way by spilling her ''immortal'' milk.