Don't ever accuse NASA scientists of not having a sense of humor.

News that the space agency's Juno probe successfully entered Jupiter's orbit after a 5-year, 540-million-mile journey resulted in not only jubilation and scientific anticipation but also the punchline to a joke originating from the early 17th century.

In 1610, Italian astronomer Galileo Galilei and German astronomer Simon Marius both discovered the four largest moons of Jupiter at roughly the same time. While Galileo generally receives the credit, the names chosen by Marius have lasted the test of time.

Writing in his journal, Marius named the moons after Jupiter's lovers — Io, Europa, Ganymede and Callisto. According to Roman mythology, Jupiter hid his infidelity from his jealous wife, Juno, by surrounding himself with a cloud. Juno, suspicious of the whole cloud thing, blew away the cover to see what was going on underneath.

The name of the NASA probe that just arrived in orbit around the giant planet? You guessed it: Juno.

"Jupiter is the Rosetta Stone of our solar system," Scott Bolton, Juno's principal investigator from the Southwest Research Institute in San Antonio, said in a mission statement. "It is by far the oldest planet, contains more material than all the other planets, asteroids and comets combined, and carries deep inside it the story of not only the solar system but of us. Juno is going there as our emissary — to interpret what Jupiter has to say."

With Juno now firmly by her husband's side, we imagine Jupiter will have plenty of explaining to do.