Vitruvius and the sun.

The Greeks did not divide the day and night as we do into 24 equal parts, but instead chose to divide day and night into twelve 'seasonal' hours. The observation had been made that that the sun always rises and sets against the same constellation of stars each 24 hour cycle.

The sun rising today in Virgo, will set in Virgo. A few months on, and the sun will rise and set in Scorpio. There will always be six constellations each night and each day,

But, by modern standards, a day made up of six hours followed by a night of six hours (each one, two hours long) would only work today, when day and night are of equal length; at the equinox.

But in the winter, the sun will rise against Sagittarius and set against Sagittarius.  The winter days will be shorter than night, and the twelve constellations will have rotated through the sky apparently at the same speed as the sun.

So, the Greeks divided the 24 hours into the twelve periods of the zodiac and accepted that the six summer night hours are shorter than the six winter night hours.

As I am pretty certain that the rotation of the stars is caused by the earth's spin I don't find any need for complicated solutions to the problem of unequal hours. A star, the sun, the moon, any planet will 'move' 15 degrees in one hour because the earth rotates 360 degrees every '24' hour period, or one degree every 4 minuets. So I have clocks that do not make any adjustment for seasonal hours, and I get on fine. Every so often the irregularities of how perihelion and aphelion change the seasons, and how many leap seconds must be added to keep the year in synch with the sun may bother me a little, but not for long.

Vitruvius clearly believed that the sun warped space and dragged the constellations around with it as it travelled the skies.  He was of the opinion that as plants and moisture are drawn towards the sun, so are the stars, I assume he believed that this force of attraction accounted for the difference in hours when time is measured against the stars.

In many ways, our own beliefs are not so different. Post Einstein, we believe that fast clocks run slow and we know that the sun keeps the earth from hurtling out into space like a billiard ball.

The main difference between the ordinary scientific view opposed to the Greek and Roman account, is that we see gravity as an effect of mass and so the attractive force is within earth, the moon and all the stars and planets. We do not see the sun as the sole regulator of the universe.