Each day of the week is ruled by a particular planet, and each of the 24 hours of a day is ruled by or comes under the influence of one of the seven planets.
There are 10 planets in number, of which Pluto, Uranus and Neptune have not been given official rulership over any sign of the Zodiac - it is only recently that Uranus is given to rule the night sign of Aquarius, who has always been under the ruler ship of Saturn and number 8; and Neptune to rule the night sign of Pisces, who has always been ruled by Jupiter Number 3. Yet, their influence and effects on earth and its inhabitants are accepted as being very potent.
So, we have 7 planets who are given rulership over the Zodiac and who aspect particular hours every day. The order in which they are lined is: Saturn, Jupiter, Mars, Sun, Venus, Mercury and Moon. The rule is that the first hour of the day is presided over by the planet under whose rulership that day comes. Since the day has been divided into 24 hours, the 25th hour naturally becomes the first hour of the next day, i.e; 1 a.m. of any day is its first hour.
On a Monday the first hour , after the 24 hours of Sunday are over, will become the first hour of the day, and will be aspected by the Moon, as Monday is Moon's Day, the second hour, 2 am, will be presided over by Saturn, the third by Jupiter, the fourth by Mars, the fifth by Sun, the sixth by Venus and seventh by Mercury.
The eighth hour will again come under the effect of the Moon and so on till the seven planet cycle ends the 24 hours of Monday under the aspect of Jupiter. The first hour on Tuesday, i.e; 1 a.m. will be aspected by Mars under whose rulership the day comes, the second by Sun and so on, as every eight hours the same planetary influence comes into effect.