The Equation of Tome

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The Equation of Tome

Post by DRatledge » Mon Dec 22, 2014 5:28 pm

The Equation of Time (the difference between Greenwich Mean Time and solar time) is zero on Christmas Day. That means at 12:00 noon the Sun is due south - or at least it is at Greenwich. For us in Bolton it will be 12:10pm. So if you want to align a new mount or pier this makes it easy to find precise north-south. A vertical stick will cast a south-north shadow at this exact time making alignment a doddle.

In reality we can do it any sunny day as all planetarium programs will calculate the time the Sun transits for your location but it's more exciting on Christmas day.

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