Source: Bewitching Ways
The planetary days are divided into 24 planetary hours with the first hour of the day beginning at sunrise and the last hour of the day ending at sunrise of the next planetary day. The period that extends from sunrise to sunset (daylight) is divided into 12 hours and the period extending from sunset to sunrise of the next day (nighttime) is also divided into 12 hours giving the 24 hours of the planetary day. However, the term Hour does not necessarily mean 60 minutes.
These influences can either help or dissolve your effort so it is important to calculate carefully.
Your planetary hours are specific to your exact location. In order to calculate your planetary hours, you will need to know the sunrise and sunset for your area. You can get this from your local newscast, newspaper or online.
Now comes the math.
1. Figure out how many minutes there will be between Sunrise and sunset
For example, say the sunrise is 6 a.m. and sunset is 8 p.m. There would be 840 minutes of daylight.
2. You then divide that number by 12 to get the number of minutes in each planetary hour of the day.
840/12= 70. So, each day planetary hour in our example would be 70 minutes long.
3. Divide your day hours into planetary hours using the minutes as your guide for increment
hour 1 in our example: 6-7:10 a.m.
Hour 2: 7:10-8:20 a.m. etc.
4. Repeat process for time between Sunset and Sunrise (for the next day) to figure out your night planetary hours.