Supermoon is nothing to worry about

Posted in Scienceon Mar 18, 2011

I read this headline today, and I wanted to respond:

‘SuperMoon’ will be closest in 18 years, prompting fears

The moon’s orbit is not perfectly circular; it is more oval shaped so that the moon sometimes is closer to the earth than others. The point of the moon’s orbit when the moon is closest to the earth is called the lunar perigee. The term people through around when the lunar perigee happens at the same time as a full moon is ‘Supermoon’, and it turns out that there will be such a supermoon on Saturday.

Supermoons actually occur pretty regularly, between 4-6 times per year. And while Saturday’s perigee is a little more extreme than it has been in 18 years, meaning the moon is the closest it has been to earth in that time, the duration of such extremity is relatively short.

I think some people hear the term ‘extreme supermoon’ and get a little freaked out, like there will be extreme gravitational forces on earth. Some will try to attribute things like the earthquake in Japan to it, but the truth is that the distance to the moon was actually further than average when the earthquake hit Japan. The supermoon will likely cause larger tides and slightly better moon viewing experiences, but most people won’t notice any effects greater than any other full moon.

If anything (and I’m not suggesting it is worth anything), we should be worried when a lunar perigee occurs at the same time as a new moon. This would occur when the moon is close to the earth at the same time the sun and moon are aligned in the same direction. We are up for one of those on October 26.

One Comment


March 18th, 2011 at 2:25 pm

People who like getting freaked out about this sort of thing should have fun on January 1, 2014, when an almost-extreme perigee will occur on a new moon within 3 days of a perihelion (which is when the earth is closest to the sun it the earth’s orbit).

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