zOwie Omega Discussion Forum

That's right, Sean, and nice diagram!

However it is only a rough guide! At 12 noon, the sun will be due south if you are on a time-change longitude, but if you are some way west or east of that line of longitude it won't quite be! When the railroads spread across America, they had trouble with exact times of arrival and departure!

Then again, you get differences with the seasons. For instance, the sun should in theory be due south-west at 3pm and indeed it is around March, but in fact in June it is quite a bit further towards the north. For the technically-minded, this is because the ecliptic is at an angle to the horizon; the higher the sun is in the sky, the greater the discrepancy.

Another factor that affects the precise position of the sun is the speed at which the earth is going round the sun. It goes faster as winter approaches and slackens off during the summer.

Complicated? Yes! Does it matter in practice? Yes, if you are going a long way by boat - you could miss that island where you were hoping to take on more provisions! If you are out wilderness walking, you'll probably be OK. But it's much better to rely on a map and good compass!

Derek