There is a discrepancy in the horary literature about the average daily motion of the planets, specifically with regard to Mercury and Venus. The problem arises because from a geocentric viewpoint, Mercury and Venus travel in “epicycles” around the Sun. Thus, the triune system of Sun-Mercury-Venus travels annually around the Earth at a mean rate of 00d 59m 08s per day, and each member of that system is allotted an average daily motion of 00d 59m 08s from the point of view of an observer on Earth.
The results of this approach are summarized by William Lilly in the following list (in Chaldean order) of the average number of degrees, minute and seconds traveled daily by each planet:
- Saturn – 2 minutes 1 second
- Jupiter – 4 minutes 59 seconds
- Mars – 31 minutes 27 seconds
- Sun – 59 minutes 8 seconds
- Venus – 59 minutes 8 seconds
- Mercury – 59 minutes 8 seconds
- Moon – 13 degrees, 10 minutes, 36 seconds
Horary astrologers other than Lilly sometimes used as the average daily motion of the planets different values for Mercury and Venus. For example, Ivy Jacobson-Goldstein used the following list in Horary Astrology Simplified (p. 5):
- Saturn – 2 minutes 0 second
- Jupiter – 4 minutes 59 seconds
- Mars – 33 minutes 28 seconds
- Sun – 59 minutes 8 seconds
- Venus – 1 minutes 12 seconds
- Mercury – 1 minutes 23 seconds
- Moon – 13 degrees, 11 minutes
I believe that Jacobson made a typo with Mars; she must have meant to write 31 minute 28 seconds. The values for Mercury and Venus, however, are not typos; they represent an alternate view of mean planetary motion. Let me explain.
To arrive at Lilly’s table, you take the distance traveled daily by each planet, adding that distance when the planet is direct and subtracting that distance when the planet is retrograde with respect to the Earth. Thus, in the course of a year, the Sun, Mercury and Venus all travel an average of 00d 59m 08s, because they travel as a triune unit around the Earth.
Ivy Jacobson-Goldstein, respecting the origins of astrology in a geocentric universe, decided to use Ptolemy’s notion of epicycles to find the average daily motion of the planets. In this system, the Sun is always traveling in direct motion around the Earth, and Mercury and Venus are revolving around the Sun; thus, these two planets will be covering more distance each day than does the Sun. It’s kind of like walking your dog; you go in a straight line but your dog goes in circles around you, thus traversing a lot more distance than you do during the walk.
In this system of epicycles, imagine that the red dot is Mercury or Venus which travel around the Sun. The Sun is the little blue dot orbiting around the Earth at a rate of 00d 59m 08s per day. Mercury and Venus are traveling at that same rate PLUS they have their own daily motion around the Sun, so that the average daily DISTANCE covered by Mercury and Venus is more than that covered by the Sun. In other words, the Sun simply has to travel in its orbit, whereas Mercury and Venus must travel along with the Sun around the Earth and must additionally travel in their own circles (epicycles) around the Sun.
To get Ivy’s values for Mercury and Venus, you would take the angular distance traveled by Mercury and Venus daily, regardless of whether they were direct or retrograde. You just want to know the distance traveled, so you don’t subtract for retrograde motion. It’s like using a pedometer. If you go for a 1 mile walk to and from your home, you have traveled two miles. You don’t go + 1 mile away from home and – 1 mile to return to your home, for an average distance of 0 miles walked. You have actually traveled 2 miles. (In mathematical terms, you add the absolute values of the distances traveled.
When you add the absolute values for Mercury and Venus traveled each day for one year, you come up with figures of about 1d 12m daily for Venus and 1d 23m for Mercury. The resulting table is consistent with the one that Deborah Houlding published in 2007, which I have slightly modified below:
| PLANET | Mean Daily Distance Traveled |
| Sun | 0° 59′ 08″ or 0.985555 degrees per day |
| Moon | 13° 10′ 36” or 13.17666 degrees per day |
| Mercury * | 1° 23′ or 1.3833 degrees per day |
| Venus * | 1° 12′ or 1.2 degrees per day |
| Mars | 0° 31′ 27″ or 0.5242 degrees per day |
| Jupiter | 0° 4′ 59″ or 0.0831 degrees per day |
| Saturn | 0° 2′ 01″ or 0.0336 degrees per day |
| Uranus | 0° 0′ 42″ or 0.026666 degrees per day |
| Neptune | 0° 0′ 24″ or 0.006668 degrees per day |
| Pluto | 0° 0′ 15″ or 0.0041666 degrees per day |
* – “Since Mercury and Venus create epicycles around the Sun, their annual average distance travelled through the zodiac will equal that of the Sun.” — Deborah Houlding.
To test this out, I picked 5 ten-day periods throughout the years from 2000 to 2005 in the Swiss Ephemeris and calculated the number of degrees traveled by Mercury, Venus and Mars during those times to find an average number of degrees per day. Here are the results of this small sample in an Excel Spreadsheet:
| Average Daily Motion of Planets – Degrees per Day – (sample of 50 days per planet) | ||||||
| Avg for | Mercury | Venus | Mars | |||
| January-00 | 10-days | 1.58166 | 1.21333 | 0.775 | ||
| May-02 | 10 days | 0.81666 | 1.33166 | 0.67 | ||
| July-03 | 10 days | 2.15166 | 1.22333 | 0.275 | ||
| September-04 | 10 days | 0.485 | 1.068333 | 0.638333 | ||
| November-05 | 10 days | 0.835 | 0.98666 | 0.35166 | ||
| Mercury | Venus | Mars | ||||
| Degrees per day | Degrees per day | Degrees per day | ||||
| Average | 1.173996 | 1.1646626 | 0.5419986 | |||
| 1d 10m 27s | 1d 9m 53s | 0d 32m 31s | ||||
Most astrology software will give planetary speeds. There is an online calculator that will give basic ephemeris data for any date and time from 1500 – 2099, including planetary speeds, at https://serennu.com/astrology/ephemeris.php
Anthony Louis - Astrology & Tarot Blog 
Hi Anthony
I am trying to understand why astrology programs use 59’08” (Sun’s motion) as the average daily motion for the Mercury and Venus and not the actual astronomical movement. I am presently writing a book and want to explain this in a way that makes sense, but I can’t get my head around this. I came across your very useful post about this which I plan to reference in my book, but was hoping you might be able to shed further light. I looked up your chart…as a fellow Virgo with my Mercury conjunct your Mercury in Leo, I am positive you are the right person to help me understand this. 🙂
Many thanks
You may have seen my post at https://tonylouis.wordpress.com/2018/08/26/average-daily-motion-of-planets-in-horary/
In the geocentric model Mercury, Venus and the Sun orbit around the Earth as a unit, so they all have the same average speed over the course of a year. On a day to day basis, the speed of the Sun is relatively constant but the speeds of Mercury and Venus vary with how fast they are orbiting around the Sun at the same time as the Sun-Mercury-Venus units is orbiting around the Earth.
OK so is it correct to say that the average motion travelled for Mercury and Venus depends on the time over which the average is taken..Eg over a year it works out to 59’08” per day, but over an actual 24 hour period they are moving much faster. Would this be a simple and accurate way to explain it?
Also I assume that this is due to the fact they are inferior planets, so it has to do with their two conjunctions with the Sun from our pov on earth per solar orbit. Would this also be a simple way to explain the difference.
The main issue is that from a geocentric perspective, Mercury and Venus orbit around the Sun at the same time as the Sun and its two “satellites” Mercury and Venus orbit around the Earth. The average daily motion figure in the tables represents the average of how far the planet travels each day, disregarding whether the planet is Rx or direct.
Sorry still confused Anthony. My chief question is why there is a difference between the 59’08” average motion, and other sources which state that the average is 1.23 for Mercury and 1.12 for Venus. i am trying to get my head around why there should be different averages listed for Mercury and Venus, eg 1.23 and 1.12 as opposed to 59.08. What is the factor that is the reason for this variation? What is it based on? I am assuming it has to do with inferior planets as they are the only two which have different averages in the literature, I wonder if it is because the average is taken over the whole synod rather than half a synod? If the average daily motion averaged over one Earth year is 59.08 then how do they arrive at 1.23 and 1.12? Sorry to be a bother.
From a geocentric perspective Mercury and Venus are always close to the Sun and must travel annually at the same rate as the Sun, Otherwise, over time Mercury and Venus would eventually be opposite the Sun, which is impossible.
The average daily rate of Mercury (or Venus), as I understand it, is based on measuring how many degrees Mercury travels each day, as viewed from the Earth, and averaging that daily figure over the course of time. Sometimes Mercury is direct, sometimes stationary, sometimes Rx (but the distance traveled is taken as an absolute value regardless of direction). The Sun in contrast is always direct and always covers roughly 1 degree per day.
Here’s an analogy. If your are traveling in a train (the Sun) which is going 10 miles per hour and you (Mercury) run from the back of the train to the front at a rate of 4 miles per hour, your rate of speed will be 14 miles per hour, but the train will keep going forward at 10 miles an hour whether you are running forward or backward inside the train.
Not sure I fully understand but perhaps starting to get a vague idea. But meanwhile I have found another reference to the speed of Mercury in Gettings Astrology Dictionary and also in Solar Fire’s software dictionary that says Mercury is 4 degrees and 6 minutes!! I have no idea how this is arrived at or why it is so much more. Still not sure why there is only a variable average for only inferior planets, since all planets travel retrograde at some point as seen from earth. I’m going to try to write something today, but think its probably a good idea if I skip the details I don’t fully understand and just reference your blog if people want more info. Thanks for your help Anthony.