High Tides during the Eclipse

A visitor to our Canada Day table noticed that the tide seem very low in False Creek and wondered if it had any connection to the Total Solar Eclipse on July 2nd in South America.

The answer is yes. A solar eclipse must happen at new Moon when the the Moon is lined up directly between the Sun and the Earth.

Image Credit: Penn State Astronomy & Astrophysics

Tides are mostly caused by the gravity of the Moon as it pulls the water on the near-side away from the Earth and pulls the Earth away from the water on the far side. With the Sun aligned with the Moon during an eclipse – the Sun is also pulling in the same direction and so the tides are larger.

Total solar eclipses are awesome events to see but not that special for tides. The same alignment and high tides occur at every new Moon regardless of whether or not there is an eclipse. Such high tides have been give the name “spring tide” (technically, spring tides also include the high tides that occur when the Moon is full)..

Other factors cause the highest tides which are colloquially known as “King Tides”. The orbit of the Moon around the Earth, and the Earth around the Sun are not perfectly circular and tides are larger when

  • The Moon is closest to the Earth – the Moon is at perigee
  • The Earth is closest to the Sun – the Earth is at perihelion

Back in Sept 2015, the above factors plus others combined to give extreme tides that will not be matched again until 2034! Read more about the Extreme Tides September 28 in 2015.