The University of Texas at Arlington

The University of Texas at Arlington

UTA Planetarium

UTA Planetarium

Ask the Astronomer Q&A

Tag: "tides"

  • Explain why high tides occur along the line joining the Earth and Moon, even on the opposite side of Earth from Moon and why low tides occur at 90 degrees to the line.
  • The moon's gravitational force pulls on water in the oceans so that there are "bulges" in the ocean on both sides of the planet, which we call high tides. The Moon pulls water toward it, and this causes the bulge toward the Moon. The bulge on the side of the Earth opposite the Moon is caused by the moon "pulling the Earth away" from the water on that side. Low tides occur at 90 degrees from the Moon because the water in the ocean has been pulled away from these locations towards the bulges that create the high tides. Since the Earth is rotating, each location will experience two high tides and two low tides every day.

    (Tags:  earth  moon  tides)