Geophysics to every area of the Earth sciences. To provide a clearer idea of what constitutes geophysics, this section describes phenomena that are studied in physics and how they relate to the Earth and its surroundings. The gravitational pull of the Moon and Sun give rise to two high tides and two low tides every lunar day, or every 24 hours and 50 minutes. Therefore, there is a gap of 12 hours and 25 minutes between every high tide and between every low tide. Gravitational forces make rocks press down on deeper rocks, increasing their density as the depth increases. Measurements
Union of the Sun and Moon Union of the Sun and Moon The Union of the Sun and Moon () is one of the Seventeen tantras of the esoteric instruction cycle () which are a suite of tantras known variously as: Nyingtik, Upadesha or Menngagde within Dzogchen discourse. "This tantra shows which experience a person undergoes in the intermediate state, the bardo, after passing away. It teaches how to resolve one's master's oral instructions during the bardo of this life, how to stabilize awareness during the bardo of dying, how to attain enlightenment through recognizing awareness during the bardo of dharmata, and, if necessary, how to