Astronomical naming conventions sky have been named from ancient times. The scientific names are taken from the names given by the Romans: Mercury, Venus, Mars, Jupiter, and Saturn. Our own planet is usually named in English as Earth, or the equivalent in the language being spoken (for instance, two astronomers speaking French would call it "la Terre"). However, it is only recently in human history that it has been thought of as a planet. Earth, when viewed as a planet, is sometimes also called by its Latin scientific conventional name "Terra", this name is especially prevalent in science fiction where the adjective terran
Planet Nine X, Planet Next, or Giant Planet Five." Planet Nine Planet Nine is a hypothetical planet in the outer region of the Solar System. Its gravity could explain the unlikely clustering of orbits for a group of extreme trans-Neptunian objects (eTNOs) that orbit beyond Neptune with average distances greater than 250 AU. These eTNOs tend to have their points of closest approach to the Sun clustered in one direction, and many of their orbits have a similar tilt. This evidence suggests that the gravity from a large undiscovered object is influencing the orbits of the most distant known Solar System objects.