Io and Europa are two of the 63 (known) moons of Jupiter.
In Greek mythology, Io was a priestess of Hera and Europa was
the queen of Crete; both were lovers of Zeus, whose Roman name was
Jupiter.
The continent of Europe is also named for Europa; the term has
been in use since at least the 1st century CE (AD). The asteroid 85
Io is also named for Io.