Tag: Accuweather

No, the "supermoon" didn't cause the Japanese earthquake

By Phil Plait | March 11, 2011 10:02 am

[UPDATE: I have posted an article with more info on the earthquake and where you can donate money toward the relief efforts.]

Japan suffered a massive earthquake last night, measuring nearly magnitude 9. This is one of the largest quakes in its history, causing widespread and severe damage. Before I say anything else, I’m greatly saddened by the loss of life in Japan, and I’ll be donating to disaster relief organizations to help them get in there and do what they can to give aid to those in need.

While there isn’t much I can do to directly help the situation in Japan, I do hope I can help mitigate the panic and worry that can happen due to people blaming this earthquake on the so-called "supermoon" — a date when the Moon is especially close to the Earth at the same time it’s full. So let me be extremely clear:

Despite what a lot of people are saying, there is no way this earthquake was caused by the Moon.

The idea of the Moon affecting us on Earth isn’t total nonsense, but it cannot be behind this earthquake, and almost certainly won’t have any actual, measurable effect on us on March 19, when the full Moon is at its closest.

So, how can I be so sure?

The gravity of the situation

Here’s the deal. The Moon orbits the Earth in an ellipse, so sometimes it’s closer to us and sometimes farther away. At perigee (closest point) it can be as close as 354,000 km (220,000 miles). At apogee, it can be as far as 410,000 km (254,000 miles). Since the Moon orbits the Earth every month or so, it goes between these two extremes every two weeks. So if, say, it’s at apogee on the first of the month, it’ll be at perigee in the middle of the month, two weeks later.

The strength of gravity depends on distance, so the gravitational effects of the Moon on the Earth are strongest at perigee.

However, the Moon is nowhere near perigee right now!

The Moon was at apogee on March 6, and will be at perigee on March 19. When the earthquake in Japan hit last night, the Moon was about 400,000 km (240,000 miles) away. So not only was it not at its closest point, it was actually farther away than it usually is on average.

So again, this earthquake in Japan had nothing to do with the Moon.

Time and tide

So why would people think this is due to the Moon?
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CATEGORIZED UNDER: Antiscience, Astronomy, Debunking

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