The planet Mercury is the closest to the sun and thereby receives its name from this proximity: Ko•chav Cha•ma, ‘The Sun’s Planet.’ The word ‘cha•ma’ is the literary name of the sun. The Latin name, Mercury, comes from a Roman god.
The planets were roughly divided in ancient times (and nowadays by the IAU, the International Astronomical Union) into two types: the Fixed stars and the Moving stars. The moving stars category includes our seven Solar System planets. They are called in Hebrew (in plural form) Koch•vey Le•chet. The singular is Ko•chav Le•chet. The word: ‘le•chet’ means ‘going’ or ‘walking.’ In Biblical Hebrew ‘le•chet’ is considered an Infinitive Absolute − the very basic, nucleus form of a word or concept. It is, hence, the core word for ‘moving.’ In fact, the mere English name ‘planet’ comes from the Greek name πλανήτης (planetes), which means ‘moving about’ (something like ‘moving back and forth’).
The other group was named by the IAU ‘the Fixed Stars.’ In Hebrew they are called Koch•vey She•vet. The singular is: Ko•chav She•vet. The word ‘she•vet’ means ‘sitting’ or ‘being settled.’ In Biblical Hebrew, ‘she•vet’ is considered an Infinitive Absolute − the very basic, nucleus form of a word or concept. It is, hence, the core word for ‘stationary.’ Of course, our current understanding is that nothing is really fixed in outer space, but because of the great distance of these stars from Earth (A•retz) they look as though they were stationary (She•vet).
Some of the planets perhaps were not known during the biblical era and do not have Hebrew names (Uranus, Neptune, and Pluto).
The IAU, indeed, changes its definitions from time to time as the science of Astronomy develops, but we still count seven planets in our Solar System and still call them ‘moving stars’ both in Hebrew and English since from the Biblical era to today.
“He who has the seven Spirits of God, and the seven stars…”