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It’s all about the wobbles

24 October, 2009

Nerds of Dublin: did you know that Dunsink Observatory runs open nights every 1st and 3rd Wednesday?

Reminds me of something...

Charlie's photo of the South Dome

The area is not great and the weather was foul, but the volunteers are keen and friendly. Sadly the sky stayed cloudy all evening, so we had a tour of their Grubb telescope (more photos) and an excellent talk by David Malone on the subject of “Why is it 21st October 2009?”. The answer is far from straightforward, taking in religion, politics, astronomy, emperors, wobbles, money, train timetables, wars, courts, nerds and all sorts 🙂

I learned that UTC, being based on atomic clocks*, is a more accurate timekeeper than the rotation of the Earth, due to earthquakes** and the like. To ensure UTC and the equinoxes match up, there’s a leap second every now and then. This means that the number of seconds between now and, say, 24th October 2030 can’t be predicted***. And you thought it was simple…

I was also reminded that our days are mostly named for the Norse gods: Wodin’s day, Thor’s day, Freya’s day and so on. How did that get past Christianity? Having just finished American Gods, this resonates…


* small wobbles

** big wobbles. Here’s an idea: if we organised worldwide marathons on the same day all running from east to west, could we affect the speed of the Earth’s rotation?

*** This sort of thing has apparently caused an argument amongst the time nerds. On one side: “The Earth is a bad timekeeper, like the pendulums and candles and sandclocks before it, and we should not be using it any more”. On the other: “Measuring the rotation of the Earth is the entire point of all this”. Discuss.

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One comment

  1. […] sky is deep, the sky is dark When we went to Dunsink Observatory, the astronomers there were keen to get us involved. “Come to Sandymount Strand next […]



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