I took art history at JMU.......................our teacher got switched to a grad student........who had to travel from UVA.............she didn't want anyone to ask her about this painting..........we all consented to her request................................

Antonio da Correggio: "Jupiter and Io" (1532). The painting depicts Jupiter in the form of a cloud as he steals a kiss from the beautiful river nymph Io.
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Kunsthistorishes 

Io

Io was a priestess of the Greek goddess Hera. Hera was the jealous wife of Zeus, the king of the gods. Zeus was very unfaithful. When Zeus fell in love with Io, he changed himself into the shape of a dark cloud to hide himself from his jealous wife Hera.

However, Hera looked down on earth and noticed the small cloud. She knew it was her husband. As soon as Hera arrived, Zeus immediately transformed Io into a white cow to avoid his wife's wrath. But Hera tied the poor cow and sent her faithful servant Argus to watch over Io. Argus had a hundred eyes and only a few were ever closed at any time.

To free Io, Zeus sent his son Mercury to sing and tell boring stories to make Argus sleep with all his eyes. Mercury told so many stories that finally Argus close all his hundred eyes. Only then did Mercury kill Argus and untie Io who ran home free. Yet when Hera discovered what had occurred, she was so furious that she sent a vicious gadfly to sting the cow forever.

Meanwhile, Io who was still prisoner into the shape of a cow could not get rid of the malicious gadfly. Finally, after Zeus vowed to no longer pursue his beloved Io, Hera released Io from her inhuman prison, and Io settled in Egypt, becoming the first queen of Egypt.

The Jovian moon Io was named for the mythological character Io by Johannes Kepler, and Simon Marius. And finally, when Voyager 1 passed Io in March 1979 and imaged the surface, the image clearly showed the hoof print of a heifer!