There are 288 discovered natural satellites – or moons, as they are colloquially known – in the Solar system. Most of these are found in the outer gas giants. However, many of these have not received proper names as they were discovered recently and have yet to be confirmed. Only 164 moons have proper names.
Out of those, there are 3 moons whose names start with the letter J. These are all listed in the following table. Below you will also find some additional details about each, including physical characteristics, the original meaning of their names, etc.
| Name | Planet | Name Meaning |
|---|---|---|
| Janus | Saturn | Roman god of beginnings, duality, time, and doorways. |
| Jarnsaxa | Saturn | A female Jötunn (giant) |
| Juliet | Uranus | Named after a charcter in Shakespeare’s play Romeo and Juliet |
Janus
Janus is a small inner moon of Saturn discovered in 1966 by Audouin Dollfus. Named after the ancient Roman god Janus who presided over beginnings and transitions, often depicted with two faces looking to the past and future. This moon shares its orbit with Epimetheus in a unique “dance” – they swap orbits every four years as they approach each other, making them the only known moons to exhibit this behavior. Janus measures about 179 kilometers across and has an irregular, potato-like shape due to its small size and weak gravity.
Jarnsaxa
Jarnsaxa is one of Saturn’s many irregular moons, discovered in 2006 by Scott S. Sheppard and his team. Named after a giantess (Jötunn) from Norse mythology who was one of Thor’s lovers. It’s a small moon, only about 6 kilometers in diameter, and orbits Saturn in a retrograde direction, suggesting it was likely captured by Saturn’s gravity rather than forming alongside the planet. Jarnsaxa belongs to the Norse group of irregular satellites, all named after figures from Norse mythology.
Juliet
Juliet is one of Uranus’s inner moons, discovered in 1986 by the Voyager 2 imaging team. Named after the tragic heroine of Shakespeare’s “Romeo and Juliet,” following the tradition of naming Uranus’s moons after Shakespearean characters. This small moon is only about 94 kilometers across and orbits within Uranus’s ring system. Like most of Uranus’s inner moons, Juliet is very dark, reflecting only about 7% of the sunlight that hits it, and is likely composed primarily of water ice and dark material.
Click on a letter below for a list of moons that begin with it.
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
Related:
For more on how moons are named check out this article.