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Skyscript Astrology Forum

The average speed of Mercury and Venus
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Deb
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Posted: Thu Jun 04, 2009 4:06 pm    Post subject: The average speed of Mercury and Venus Reply with quote

Can anyone help with this problem, or point me to some good web links?

I am having trouble finding a reliable and reputable source of information regarding the average daily velocity of Mercury and Venus. Software programs such as Janus seem to average out their motions to that of the Sun, obviously because they travel with the Sun as it journeys through the zodiac. This means that Mercury, the Sun and Venus, all become defined as ‘fast in motion’ when they start to travel more than 0°59 per day. But it doesn’t make sense to consider Mercury as moving more quickly than usual at this rate, when it can travel up to 2°15 per day.

At first I thought it might be a simple matter of taking the mean value between 0° (when Mercury is stationary) and its highest value of 2°15, which would mean that Mercury becomes ‘fast in motion’ at 1°07 or thereabouts. But I realise this can’t be the way to decide the average speed, otherwise Venus would have the mid-value between 0° (stationary) and its top speed of 1°15’, which would make its average less than 40 minutes per day, which is slower than the Sun.

I am probably approaching this from a ridiculous direction, but if you realise I am, please point it out to me in simple language Smile You see another problem is that all the astronomical documents I have found on the web use different ways to describe the planetary speed. Astronomers don’t seem to like working in longitude anymore...

I'll be grateful for any comments on this
Deb
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margherita



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Posted: Thu Jun 04, 2009 4:17 pm    Post subject: Re: The average speed of Mercury and Venus Reply with quote

Deb wrote:

I am having trouble finding a reliable and reputable source of information regarding the average daily velocity of Mercury and Venus. Software programs such as Janus seem to average out their motions to that of the Sun, obviously because they travel with the Sun as it journeys through the zodiac. This means that Mercury, the Sun and Venus, all become defined as ‘fast in motion’ when they start to travel more than 0°59 per day.
Deb


My notes from Cida lessons- from Giancarlo Ufficiale of CieloeTerra say the same as Janus 0.59'08''

I believe he is trustworthy Smile

Margherita
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Deb
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Posted: Thu Jun 04, 2009 4:29 pm    Post subject: Reply with quote

That was quick Smile But I don't think that is right Margherita.

I understand why this is being done, because it is assuming that the Sun, Mercury and Venus are all moving as a unit, so that the three of them progress through the zodiac - on average - at the same rate.

But as the Sun is moving in a direct and (more or less) constant motion, Mercury and Venus are travelling around the Sun, and Mercury can cross over 2 degrees of the zodiac per day. I don't think that, when it is travelling at only 1 degree per day, Mercury is moving more quickly than its own average. I think it should really be defined as 'slow in motion' at that rate.

I vaguely remember someone raising this in the forum a couple of years ago. A female member (the name escapes me) had done a lot of personal calculation to work out what the true average velocity should be. But I've searched and can't find the post, which is very frustrating !
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Eddy



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Posted: Thu Jun 04, 2009 4:30 pm    Post subject: Reply with quote

I'd believe the average speed of Mercury and Venus should be the same as the Sun's. Mars, Jupiter, Saturn and further get behind. The inner planets get behind too after the moment of greatest evening elongation but these planets always catch up with the Sun after a while each time after greatest morning elongation.

As the Sun 'moves' with different speed through the zodiac it can be considered that at the moments of greatest elongations the inner planets move with the same speed as the Sun, the speed of that moment would be the 'average' (momentary) speed.
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Olivia



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Posted: Thu Jun 04, 2009 4:33 pm    Post subject: Reply with quote

It's occasionally unnerved me to see Mercury listed as 'fast' in astrology proggies when it's retrograde. Somehow I don't think you could really count that as a plus on the dignities table.

It makes sense to me that Mercury and Venus are tied to the Sun's motion, as well, even the ideas of their being fast or slow moving.
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Deb
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Posted: Thu Jun 04, 2009 4:41 pm    Post subject: Reply with quote

I thought you at least would see things my way Eddy Sad

Can anyone understand my point? Many of the astrological significations of Mercury come from the fact that it moves so much more quickly than the other planets (apart from the Moon). Mercury is known to be a quicker moving planet than the Sun, and whilst the Sun is moving forward in a constant direct motion, Mercury is moving forwards, then going backwards for a while, before moving forwards again to get to the same place as the Sun at the same time as the Sun.

0.59 might be OK as an annual rate of movement, but it has to be wrong as an average *daily* motion.
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Deb
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Posted: Thu Jun 04, 2009 4:45 pm    Post subject: Reply with quote

Hi Olivia

Sometimes it matters to be able to tell whether a retrograde planet is moving fast or slow, and this can have meaning even though it doesn't negate the retrograde significance. For example, Venus retrograding toward the Sun might signify the return of a woman to her husband after they have parted, and even though it is accepted that the return is a begruging one, if Venus is fast it suggests she will return with less reluctance than if it is slow.

This is an example where we can't just assume the Sun's motion as setting the standard for whether Venus' is fast or slow. Each planet has an average daily motion in its own right, and I am happy to accept the value 0.59 for Mercury and Venus - but for any other reason than that it is the average daily motion of the Sun! Smile
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Deb
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Posted: Thu Jun 04, 2009 5:18 pm    Post subject: Reply with quote

OK, I searched a bit harder and found the older thread - it was posted by Aquarianessence (Connie) and she analysed the data for a year to get an average mean movement for Mercury of 1°14'39" per day.

This link goes to the second page of the thread where she gives her results
http://skyscript.co.uk/forums/viewtopic.php?t=3208&start=15

I think that Connie absolutely has this right, and that Mercury does not become 'fast in motion' until it goes over that speed.

I just wish she'd done the same calculation for venus because it looks like this information isn't easily available elsewhere. Maybe I'm wrong though. If I can get the data for Venus I will add it to the glossary along with a note about how the average daily motion uses a different notion of Mercury and Venus' speed to the average annual motion which is tied to the speed of the Sun.

Thanks for the contributions so far.

Deb
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Eddy



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Posted: Thu Jun 04, 2009 5:32 pm    Post subject: Reply with quote

Cheer up Deb Smile , perhaps there's indeed another way to look at it. When I was 10 or so there regularly were humoristic unusual car races on tv with the only difference from the normal ones that it was required that the cars drove backwards. It was a race though.

So going backwards doesn't need to be associated with 'slow'. I can't say how fast an average speed would be. A heloicentric comparison with the Earth would give a speed over 3 times faster than the Earth's, but I believe that is too fast.

Another method, related with these car races could be that any movement wether forwards or backwards counts. The 'stations' are to be considered slowest because the planets barely move through the zodiac. In adding up the total of arcminutes per day when moving direct, the backward motion could be considered as positive motion and then (the average of this speed) added to that of the direct speed. However, I'm not sure if this is a good option.
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johannes susato



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Posted: Fri Jun 05, 2009 7:36 am    Post subject: Reply with quote

Because every status of the planets movement has its own astrological meaning, their average speed schould be listed and considered threefold in my opinion:

One. The average speed of direct movement (that means from the first moving after station to the last moving before station to retrograding).

Two. The average speed of retrograde movement (from first moving backwarsds or retrograde after first station to the stop in second station).

Three. The stationary status is no speed and should not be counted for direct or retrograde speed of movement.

Only this threefold viewing or treatment would respect the special needs for astrological judgements of the planet's particular status. Thus we get a reference for the condition of a planet in its particular status 'direct' or 'retrograde' ('stationary' has and needs no average).

We don't drive a race and judging a chart we don't need the astronomical 'true' speed as a reference, because we know that Mercury and Venus ascorting the Sun must have the same speed as him.

Johannes
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Deb
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Posted: Fri Jun 05, 2009 8:44 am    Post subject: Reply with quote

I’m shocked. I had started writing out a long post and then checked the glossary, only to find that I published the details I was looking for years ago!!

See this page:

http://www.skyscript.co.uk/gl/slow.html

The responses I had made to Eddy and Johannes don’t need to be made now, but at least I can suggest a reason why Mercury’s average speed seems to be 1 minute different to what Connie calculated. So I am going to cut into some of the comments I have written this morning. (My Virgo Moon won’t allow me to waste them)…

For interpretation purposes, we need to know whether a planet is moving at its average rate of motion, or at a pace that is faster or slower than usual.

The generally reported average of 0°59 for Mercury and Venus has nothing to do with their average rate of motion. This only tells us the average rate of progression through the zodiac per year, broken down to a daily rate. Their rate of progression through the zodiac is not the same as their speed of motion, because they move backwards and forwards at the same time that the Sun is moving steadily in a direct course along its path.

It’s easy to obtain the Moon’s average rate of motion because, like the Sun, it never goes retrograde, and travels through the ecliptic without having to simultaneously circle around the Sun.

The speed of the other planets is dependent upon where they are at in their synodic cycles, so for the inferior planets we should determine the average rate of motion throughout a complete cycle from superior conjunction through inferior conjunction and back to superior conjunction. After that we would just be repeating work for no reason.

I think that the average rate of motion for the superior planets needs to be checked too, in case the usually reported figures are showing the rates of zodiac progression rather than the average speed.

I think this work needs to be done (for my sanity), and then software publishers should be forced to update their tables (even if they have only just released a new update) and all authors should be forced to correct the values given in books that say that Mercury’s average rate of motion is 0.59 per day, (or they should have their books pulped). Christian Astrology is safe because I’m working on a new edition which will have this information in a footnote (all other editions will be pulped). This seems the most reasonable course of action to me.

Does anybody want to do the work?
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Eddy



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Posted: Fri Jun 05, 2009 12:00 pm    Post subject: Reply with quote

The average motion of 1° per day doesn't give me sleepless nights, I still think it as a pretty good one. I'd consider Mercury and Venus as fast planets anyway, at least in respect to the Sun, either they approach the Sun in a fast way or quit him, backwards or forwards both are fast.

By the way Deb, are you searching for a definition specifically for horary purposes, or is this also used for natal chart delineation?

What is the rationale for Mercury 1°23'per day in your table? I get the rationale of Connies/AquarianEssence's 1°14'39"/day but your's is 0°8' faster.

From a heliocentric view one could take Mercury's speed as ca. 4°/day and Venus's 1.5°/day but these seem a bit large, especially Mercury.

Another method I can imagine that one takes the number of synodic periods it takes to get a similar position on the same calendar day.
For Mercury, 41 periods in 13 years or more exact 145 in 46 years. Dividing the former by the latter gives ca. 3°/day which still is a bit fast.
For Venus 5 synodic periods in 8 years gives 1.6°.



Deb wrote:
I think this work needs to be done (for my sanity), and then software publishers should be forced to update their tables (even if they have only just released a new update) and all authors should be forced to correct the values given in books that say that Mercury’s average rate of motion is 0.59 per day, (or they should have their books pulped). Christian Astrology is safe because I’m working on a new edition which will have this information in a footnote (all other editions will be pulped). This seems the most reasonable course of action to me.

Does anybody want to do the work?

I'll have to think a while about it before pulping all my astrology books, furthermore I should follow a brainwash programme at some former KGB agents to forget what I thought about the 1° average Smile.
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johannes susato



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Posted: Fri Jun 05, 2009 12:27 pm    Post subject: Reply with quote

Deb wrote:
For interpretation purposes, we need to know whether a planet is moving at its average rate of motion, or at a pace that is faster or slower than usual.

The generally reported average of 0°59 for Mercury and Venus has nothing to do with their average rate of motion. This only tells us the average rate of progression through the zodiac per year, broken down to a daily rate. Their rate of progression through the zodiac is not the same as their speed of motion, because they move backwards and forwards at the same time that the Sun is moving steadily in a direct course along its path.

The speed of the other planets is dependent upon where they are at in their synodic cycles, so for the inferior planets we should determine the average rate of motion throughout a complete cycle from superior conjunction through inferior conjunction and back to superior conjunction. After that we would just be repeating work for no reason.


Hi Deb,

IF the character of a movement (direct, retrograde, station) has its own quality and astrological meaning - and it has in my opinion - then every of the three movements should be considered apart concerning an avarage speed. Otherwise you would melt what is different and should be treated different then. Station has not the least meaning for the speed of a direct or retrograde moving planet. So it should not be taken into account for the calculation of the avarage speeds, which are to be calculated twice: one calculation for the direct movement, the other for the retrograde movement as I tried to explain in my text above.

And then you could compare the avarage retrogradation-speed with the speed of the Venus retrograde in your example obove of the woman coming back to her husband and judge, whether this will be without delay or not.

Regards
Johannes
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Deb
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Posted: Fri Jun 05, 2009 12:58 pm    Post subject: Reply with quote

Eddy wrote:
The average motion of 1° per day doesn't give me sleepless nights,


Sleepless night. Note: one, so far. You make me sound like a mad woman…

Quote:
I still think it as a pretty good one. I'd consider Mercury and Venus as fast planets anyway, at least in respect to the Sun, either they approach the Sun in a fast way or quit him, backwards or forwards both are fast.


No, its not. It is good enough for the Sun, because it is supposed to be the actual value for the Sun (actually 0.59, not 1°). But the Sun’s motion doesn’t vary much, so we are never far wrong taking an average measure of 1° for the Sun. But Mercury and Venus both move faster than the Sun, on average. So how can you not see the problem as I see it?? I think you have to forget about the backwards and forwards bit, planets go fast or slow regardless of whether their motion is direct or retrograde. (Also, planets don't go a minus speed if they go backwards - I have seen some people assume that!)

Quote:
By the way Deb, are you searching for a definition specifically for horary purposes, or is this also used for natal chart delineation?


The information is used a lot in horary, but it’s a bog standard traditional principle that planets are essentially dignified when travelling faster than usual and accidentally debilitated when slower than usual. Janus defines Mercury as ‘(F) fast in motion’ when travelling a second faster than 0.59, but at this rate Mercury is travelling slower than its usual daily rate, not faster.

Quote:
What is the rationale for Mercury 1°23'per day in your table? I get the rationale of Connies/AquarianEssence's 1°14'39"/day but your's is 0°8' faster.


Oh, I hadn’t noticed that the figures were so far apart, I thought Connie had established 1°24. I don’t know the rationale for the figures in the table, except that I must have taken them from what I thought at the time was a reliable source (I don’t make these figures up). But now it seems that at least one of these is faulty. The only way to calculate this correctly as far as I’m concerned is this:

For Mercury take the daily motion for each of the 116 days of its synodic cycle, add all the distances together and then divide by 116. That seems to me to be the only way to get a reliable figure for how much Mercury moves in longitude, per day, on average.

I’ll try to remember where I found the figures, and come back later with that if I can.

Quote:
From a heliocentric view one could take Mercury's speed as ca. 4°/day and Venus's 1.5°/day but these seem a bit large, especially Mercury.


Eddy, you obviously have a problem with this heliocentricity nonsense. The astrological use of this is entirely dependent upon the way the planets look, and appear to move, as we observe them from our uniquely geocentric viewpoint. That's why all the astronomy sites are so unhelpful nowadays, because they don't cater to the geocentric perspective anymore, and don't give the planetary motion as a distance travelled in longitude anymore. (They should be pulped too).

Johannes, I don't think I quite follow your argument, and maybe that is down to the simplicity of my mental faculties. Have I made it any clearer in saying that I am hoping to establish how far each planet moves in longitude, per day, on average? Anything on top of that would be a bonus.

Regards
Deb
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pankajdubey



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Posted: Fri Jun 05, 2009 1:41 pm    Post subject: Reply with quote

I am so daft that I don't even understand the question crying

I have this Astrowin 3.1 freeware-which gives me the speed and Rate of planets:



What am I missing here or what additional data is needed ?


PD
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