The same god under two names. Zeus is the Greek king of the gods; Jupiter is his Roman counterpart, and the Romans identified the two directly as their mythologies merged. Jupiter is also the name of the largest planet, following the Roman convention used for the planets generally.
The core difference
Greek and Roman religion converged over centuries, and Roman writers systematically matched their own gods to Greek ones. Zeus and Jupiter are the clearest case: king of the gods, wielder of the thunderbolt, god of sky and law.
- Zeus — Greek, son of Cronus and Rhea, ruling from Mount Olympus
- Jupiter — Roman, also called Jove, chief god of the Roman state
The wider pairings
- Hera → Juno
- Poseidon → Neptune
- Ares → Mars
- Aphrodite → Venus
- Hermes → Mercury
- Artemis → Diana
The pairs are not perfect. Mars was an agricultural and civic deity of real standing in Rome before he was matched to Ares, who the Greeks regarded with considerably less warmth.
Why the planets use Roman names
The naked-eye planets carry Roman names — Mercury, Venus, Mars, Jupiter, Saturn — because that is the tradition Latin astronomy passed to medieval and then modern Europe. The convention held for later discoveries: Neptune is Roman, and Uranus is the exception, being the Latinised form of a Greek name.
The words they left in English
- jovial — from Jove, once meaning born under Jupiter's influence and so cheerful
- martial — from Mars
- mercurial — from Mercury
- by Jove — a mild oath that avoided naming a god directly
Frequently asked questions
Are Jupiter and Zeus the same god?
Yes — the same figure under Roman and Greek names. Roman writers identified their Jupiter with the Greek Zeus as the two mythologies merged.
Why is the planet called Jupiter and not Zeus?
The planets carry Roman names because Latin astronomy passed the tradition to modern Europe. Uranus is the exception, being a Latinised Greek name.
What does "jovial" have to do with Jupiter?
It comes from Jove, another name for Jupiter. To be jovial was to be born under his influence and therefore cheerful.