Soluret ved midsommer kl 17

Sundials

The sundials differ on where on the earth’s curved surface they are placed.

 

The sundial consists of different lines to indicate the time of year and time of day.

 

The time of year is shown by the three main lines, which is the summer solstice line, equinox line and the winter solstice line.

 

A calendar consists of months, but these are not symmetrical about the solar year – which is approximately 10 day difference between the winter solstice and New Year

 

The time of day is shown by the loops – why is it loops and not lines? This is because the earth moves in an ellipse, not a circle around the sun. In an ellipse, the speed is higher, near the sun and less, distant from the sun, this means that when you measure the time with an accurate clock, what we do today, this timedifference is visible – in the past, when watches were not common, it did not matter by 10 – 20 minutes more or less.

 

If you look at the sun visor a certain time every day of the year, it will follow this loop curve around, but which way round? – If you stand in front of the sundial with the sun in the back, then the first calendar quarter is the left curve, the second quarter will be  the right curve etc.