Correction for Place of Birth

There's still one more minor correction for the computer to make. The computer already corrected for the difference of four minutes between sidereal time and a solar day if you were born in Greenwich, England. But because most of us are born elsewhere, the computer corrects for these four minutes again, based on our location. In essence, this is a correction for the place of birth, and, if we remember that distance equals time, this makes sense.

44 minutes 1 sec 37 minutes 56 sec


Acceleration is a correction factor to compensate for the difference of about four minutes between a solar day and sidereal time. Acceleration is calculated for both the time of birth and place of birth.

To calculate this, the computer is going to add 10 seconds for every 15 degrees of west longitude. Spielberg was born at 84W31, so for the first 75 degrees of west longitude, it adds 50 seconds. That leaves another 9 degrees and 31 minutes to correct for, which is about 6 seconds, for a total correction of 56 seconds. The computer then adds the 56 seconds to the rest of the corrections and adds them all up to get the actual sidereal time for Spielberg's birth. So now we have:

Sidereal time shown in ephemeris: 5 hours 44 minutes 1 sec

True local time (past midnight): 17 hours 37 minutes 56 sec

Acceleration (based on time of birth): 2 minutes 56 sec

Acceleration (based on place of birth): 56 sec

Actual calculated sidereal time: 22 hours 83 minutes 169 sec

This converts to 23 hours, 25 minutes, 49 seconds, which is the final sidereal time for Spielberg. Hooray! We finally have the number we need!

The computer also knows that once the sidereal clock reaches 24 hours, it starts counting over again beginning at 0. So it checks to make sure that the final sidereal time is within 24 hours. If it's not, it subtracts 24 hours from the total to get the correct sidereal time. In Spielberg's case, this wasn't necessary.

Let's summarize the corrections the computer makes for North American charts, using a midnight ephemeris in order to arrive at sidereal time:

1. The computer starts with the reference sidereal time in the ephemeris for the date and year of birth.

2. Then it calculates the true local time for the birth place. It then expresses that birth time in a 24-hour system (adding 12 hours for p.m. birth times), and adds that to the sidereal time it found in the midnight ephemeris.

3. Now it calculates and adds the acceleration factor to compensate for the difference of four minutes per day between sidereal time and regular clock time, based on the birth time.

4. The computer calculates the acceleration factor again to compensate for the birth location and adds this, too.

5. Last, the computer adds all of the above and converts it to within 24 hours to get the final calculated sidereal time.

The Art Of Astrology

The Art Of Astrology

Get All The Support And Guidance You Need To Be A Success With Astrology. This Book Is One Of The Most Valuable Resources In The World When It Comes To A Look at Principles and Practices.

Get My Free Ebook

Post a comment