Poseidon is one of the eight hypothetical planets (sometimes referred to as the trans-Neptunian points or planets, or TNPs for short) utilized in Uranian astrology. The Uranian system, sometimes referred to as the Hamburg School of Astrology, was established by Friedrich Sieggrün (1877–1951) and Alfred Witte (1878–1943). It relies heavily on hard aspects and midpoints. In decline for many decades, it has experienced a revival in recent years.
On the one hand, Poseidon is mind, spirit, and ideas; on the other, it is enlightenment, inspiration, spirituality, and “vision.” Thus, for example, a Mercury-Poseidon connection may indicate spiritual perception; Venus-Poseidon connection, pure love, or religious faith.
in Greek mythology, a son of Cronus and Rhea, one of the most important Olympian gods and lord of the seas, which he controlled with his trident. Poseidon was honored in Athens as patron of the city’s navy; the main part of the Erechtheum on the Acropolis in Athens was dedicated to him, as was the temple on Cape Sounion. Poseidon was also considered the patron of horsemen and of chariot races, which were part of the Isthmian games. In Roman mythology Neptune was Poseidon’s counterpart.