In the Kabbalah (the ancient Jewish tradition of mystical interpretation of the Bible, first transmitted orally and using esoteric methods (including ciphers)), it is down through the ten spheres or Sephiroth, which represent the creative emanations of God's innermost being, that the Divine Light is refracted and reflected. These make up the Sephirotic Tree of Life, which unfolds the hidden structure of God, humanity, and the universe, which in the En Sof (God), the Infinite, are inseparably one. The Divine Light which is reflected in the Sephirotic is like the light of the sun which is reflected in the heavenly spheres, and so each of the seven lower spheres in the trees is associated with one of the heavenly bodies.
In the diagram, each has its astrological sign according to the system used by Athanasius Kircher (German Jesuit scholar): Tifereth-Beauty-Sun, in the center, and beneath, Hod-Splendor-Venus, Netsah-Firmness-Mars, Yesod-Foundation-Mercury, Malkuth-Kingdom-Moon, and above, on the left, Din or Gevurah-Judgement-Saturn, and on the right, Hesed-Love-Jupiter.
This astrological symbolism is also found in the Menorah (previous post), which is shown in a traditional Kabbalistic diagram with the Hebrew letters for the Sephiroth on its stem and branches.
The Sephiroth related to the Menorah. (Bibliotheque de l'Alliance Israelite Universelle.)