Tuesday, April 5, 2016, 12:43 PM - Earth won't be seeing much of the Moon on April 7, but its influence will certainly be felt, as the closest new moon of 2016 brings King Tides to Canada's coastlines.
Night by night this week, the Moon is becoming a thinner and thinner sliver in our night skies, until it disappears from view on April 7 - lost in the daytime sunlight, in its "new" phase. At the same time, the Moon is drawing closer and closer, so that by just before noon EDT on that day, it will reach its closest distance to Earth since the September 27 Super Moon Eclipse, resulting in the closest "perigee new moon" of 2016.
When this happens, the stronger gravitational pull from the Moon on Earth's oceans will cause one of the largest tidal variations of the year, known as the King Tides.
While tides vary greatly based on the location, the most extreme tides in Canada will be seen in Bay of Fundy, between New Brunswick and Nova Scotia. With the highest tides in the world, on an average day the Bay of Fundy sees a range from around 2 metres at low tide to around 15 or 16 metres during high tide - a difference of around 13-14 metres. On Thursday and Friday, low tide will drop to less than 1 metre and high tide will rise to over 17 metres - a difference of over 16 metres, or high enough to flood a 4 or 5 storey building!
What is going on behind King Tides?
Tides are a regular fact of life for Canada's coastal regions. The waters along our shores advance and retreat twice every day, swelling even higher and dropping even lower twice every month, and there's even a cycle to them that requires a yearly calendar to track.
King Tides are exceptional tides - the highest and lowest tides, resulting in the largest tidal variation of the year - which happen roughly twice every year.
So, what goes into making the King Tides? It's the gravitational "dance" of the Earth, the Moon and the Sun.
As the Moon orbits around the Earth, the planet and everything on its surface feels a varying amount of pull due to the Moon's gravity - stronger on the side facing the Moon and weaker on the side opposite to the Moon. This is a fairly weak effect when compared to the gravitational pull of the Earth, especially on the small-scale, so we barely notice it and it has a minuscule effect on petty much everything else around us. When you apply this pull across larger scales, such as the diameter of the Earth, however, and have it acting upon the kilometres-deep fluid filling Earth's oceans, the collective effect of the Moon's gravity on all of those individual water molecules adds up.