A priestess of Hera who was loved by Zeus. Trying to protect her from the jealousy of Hera, Zeus turned Io into a heifer. Hera sent a gadfly to torture the heifer, which then fled across the world and finally reached Egypt, where Zeus turned her back into human form.
One of the Galilean moons of Jupiter, the fifth closest satellite to the planet. It is actively volcanic, colored red and yellow with sulfur compounds, and has a diameter of 2,526 miles (3,630 km).