|
Hi Alex
Well, yes, but maybe no?
This strange answer is due to how we all synchronise our timepieces using the Standard Time Zones on the Earth. We know the following:
There are 24 hours in a (mean) solar day.
There are 360 degrees in one rotation of the Earth.
Dividing 360 deg by 24 hrs we get 15.
That is, in 1 hour the Earth rotates 15 degrees. This is the equivalent to traversing a Standard Time Zone.
This means that for every 4 minutes of time, the (mean) Sun will appear to move 1 degree in the sky, along the ecliptic.
If you happen to live right on a Time Zone meridian e.g. 150 deg E, then I believe noon will be 12 noon local time (AEST) when the shadows cast by the Sun will be at their smallest. (There is an additional complication called the “Equation of Time” which takes into account the apparent speeding up and slowing down of the Sun in its journey across the sky throughout the year, due to our elliptical orbit around the Sun).
However, as I live in Brisbane at a longitude of 152 deg E, the Sun will arrive at my local meridian at noon local time, some 2 degrees before it would arrive at the 150 deg meridian.
So, noon for me at 152 degrees E would be 11:58am local time (shortest shadows).
Noon for an observer at 150 degrees E would be 12:00am AEST (shortest shadows).
Noon for an observer at 145 degrees E would be 00:20pm local time (shortest shadows).
However, it would be impractical if we had to set our time pieces according to our local time so the politicians deemed that if we live somewhere in the Time Zone centred on 150 deg, we will all follow AEST and not our local time. That is, if we observe or live within ±7.5 degrees of 150 deg E, (142.5 to 157.5 deg E), our timepieces are set to synchronise with the local noon at 150 degrees E.
So, the worst case scenario would be:
At 157.5 deg E, the shortest shadows will be at 11:30am AEST.
At 142.5 deg E, the shortest shadows will be at 00:30pm AEST.
Cheers
Dennis
|