skyscript.co.uk
   

home articles forum events
glossary horary quiz consultations links more

Read this before using the forum
Register
FAQ
Search
View memberlist
View/edit your user profile
Log in to check your private messages
Log in
Recent additions:
Godfather of Modernity: The Alan Leo Legacy Vol. One - Early Astrological Journals 1890-1912, compiled by Philip M Graves
Reviewed by Deborah Houlding
Lilly's Considerations
compiled by D. Houlding
Book II of Carmen Astrologicum by Dorotheus
translated by David Pingree
Compiled by Deborah Houlding
The Babylonian Astrolabe: the Calendar of Creation, by Rumen K. Kolev
Reviewed by Gill Zukovskis

Skyscript Astrology Forum

Absolute maximum declination of each planet
Goto page 1, 2  Next
 
Post new topic   Reply to topic    Forum Index -> Philosophy & Science
View previous topic :: View next topic  
Author Message
Helmut Licht



Joined: 10 Mar 2010
Posts: 1
Location: Baltimore

Posted: Wed Mar 10, 2010 12:31 pm    Post subject: Absolute maximum declination of each planet Reply with quote

Hi - Does anybody know what the absolute maximum declination of the planets is? By absolute I mean at least the last millenium or two and the next two - longer periods if possible.
Helmut
_________________
Dancing with the stars to the music of the spheres.
Back to top
View user's profile Send private message Send e-mail
dr. farr



Joined: 26 Sep 2009
Posts: 276
Location: los angeles, california usa

Posted: Sat Mar 27, 2010 8:39 am    Post subject: Reply with quote

Refer to the "Maximum declination of planets" thread in the Nativities section of the Forum.

http://skyscript.co.uk/forums/viewtopic.php?t=5101
Back to top
View user's profile Send private message Send e-mail
Deb
Administrator


Joined: 11 Oct 2003
Posts: 3917
Location: England

Posted: Tue Mar 30, 2010 9:45 am    Post subject: Reply with quote

Since the planets orbit the Sun, I suppose that their maximum declinations can be simply found by adding the obliquity of the ecliptic to their maximum latitudes north or south of the ecliptic.

E.g., the Sun's maximum declination from the equator is currently 23°30', and Jupiter's furthest latitude north of the ecliptic is 1°38', hence Jupiter's maximum declination north is 25°08N. But Jupiter can reach latitude 1°40' South so its maximum declination south is 25°10.

I'm not sure if the obliquity of the ecliptic is exactly 23˝° but I know that is fairly accurate for the next 100 years.

(I wasn't sure where to post this comment, but chose this post because the other one is quite old now).
Back to top
View user's profile Send private message
Eddy



Joined: 04 Feb 2009
Posts: 922
Location: Netherlands

Posted: Tue Mar 30, 2010 11:58 am    Post subject: Reply with quote

I'm afraid it's slightly more complicated Deb. First, since the obliquity of the planets is a heliocentric matter, the latitude as seen from Earth will vary with the planet's distance from Earth. Here http://www.astro.uu.nl/~strous/AA/en/reken/hemelpositie.html
in table 1 the inclination i is the obliquity. There we see that Venus' obliquity is 3.395°, however seen from Earth Venus' latitude can be up to 8 degrees or even 9. This is the case when the maximum occurs the same time when Venus is closest to Earth. Just look in the ephemeris from 1 year ago now. Just like when someone is close appears longer than seen from a distance, even when this person walks at a same distance from a central point (live Venus around the Sun). Same is with Mars, at some oppositions latitude is ca. 4°. Mercury is the other way round. Although his inclination is 7°, we will never see this from Earth because his distance is always greater than his distance from the Sun. For the far planets the differences are much smaller but in case of Jupiter still noticeable.

Second:
Deb wrote:
E.g., the Sun's maximum declination from the equator is currently 23°30', and Jupiter's furthest latitude north of the ecliptic is 1°38', hence Jupiter's maximum declination north is 25°08N. But Jupiter can reach latitude 1°40' South so its maximum declination south is 25°10.
This will only occur when the ascending node of Jupiter is in the direction where we locate 0°Aries. Then the latitude (if we ignore the first effect for a moment) will add up to the maximum declination when Jupiter is in 0°Cancer. If the descending node would be there, then the latitude should be subtracted from the max decl. The movement of the nodes is very slow and rather unnoticeable in a lifetime. Pluto for example with the inclination 17° can theoretically have 23.5+17=40.5° declination at0°Cancer. However nowadays Pluto's ascending node is not in 0° Aries but in 110,307 or 20°18'Cancer. If I remember well the maximum declination of Pluto is now ca. +23.5° but not in 0°Cancer but somewhere in the middle of Leo.

The mean obliquity of the ecliptic is now ca. 23°26' and it slightly diminishes and also wobbles a bit because of nutation. In the future it will increase again but it wobbles somewhere between 22 and 24 something.

There were more threads on this. Dr. Farr mentioned one of them but I remember that about over 1 year ago someone had posted a self drawn illustration to explain the first issue above.
Back to top
View user's profile Send private message
Deb
Administrator


Joined: 11 Oct 2003
Posts: 3917
Location: England

Posted: Tue Mar 30, 2010 12:39 pm    Post subject: Reply with quote

Hi Eddy
Well I just wrote that down as I thought of it, so it wouldn't surprise me at all if the real situation were more complicated. But my problem is that I don't understand your post, or why you see this as a heliocentric matter. The whole thing is a geocentric matter (in my head), since we are concerned about measurements as we make them from the Earth. So I assume that we are talking about 8 or 9 degrees for Venus, as being the limit of latitude from the ecliptic which is recorded in traditional astrological texts. The "obliquity" of 3.395° which you refer to doesn't mean anything to me.

Hence - if the Sun cannot rise higher than 23°26 north of the equator, and Jupiter cannot move more than 1°38 north of the Sun's path (presuming these figures are accurate) then surely Jupiter cannot rise more than 25°08 north of the equator? I know you said that what I wrote "will only occur when ... " but Helmut asked about the absolute maximum. Am I wrong, or are we simply using different frames of reference?
Back to top
View user's profile Send private message
Eddy



Joined: 04 Feb 2009
Posts: 922
Location: Netherlands

Posted: Tue Mar 30, 2010 1:07 pm    Post subject: Reply with quote

Sorry if I'm too unclear, that's because I try to be brief. Yes we deleneate astrology geocentrically, yet the effects we see are because of heliocentricity. Just think of Venus never being further from the Sun than 48°. We use it geocentrically but the effect is explained heliocentrically.

You can do something to imagine this. If you stand in a field with someone. Ask the person(A) to walk around another person(B) and to keep distance from this person(B) always 7 metres. You stand 10 metres from the tree. (These distances are same equivalence of Venus v. Earth, 0.7 v. 1.0 astronomical unit distance to the sun(person(B)).

As person(A) walks around person(B) you will see that A will never be further than ca. some 45° from B. B will see A walking circles. And not only that when A is close to you, in the middle between you and B (s)he will appear bigger than when far behind B. In the former it will be 10-7=3 metres distant and on the latter case 17 metres. As seen from B person A will always appear as of same length because the distance is always 7 metres. That's why at inferior conjunction (Venus is then 0.3 Astronomical Units close) she will appear higher in latitude than from the Sun.
Back to top
View user's profile Send private message
Deb
Administrator


Joined: 11 Oct 2003
Posts: 3917
Location: England

Posted: Tue Mar 30, 2010 1:25 pm    Post subject: Reply with quote

I understand that Eddy - it is our geocentric perspective of these heliocentric events that causes the apparent shifts of speed and light (as seen from Earth). But I am not sure how this relates to the example I gave for finding the absolute maximum declination limit, so I am still wondering if the example I gave earlier is actually wrong or just utilising a different approach to the one you are used to.

So let's do anotehr quick example. If Venus cannot move further than 9° above the ecliptic (I think it is just over but let's keep it simple here) then her maximum declination (under the most extreme circulmstances) will be about 31°. She will hardly ever reach this limit, but shouldn't be able to move beyond it. I'm not suggesting that is *precise* but my suggestion concerns whether it is a fairly reliable 'rough and ready' rule, or not?

I suppose Helmut could get his ephemeris out and check Smile
Back to top
View user's profile Send private message
Eddy



Joined: 04 Feb 2009
Posts: 922
Location: Netherlands

Posted: Tue Mar 30, 2010 1:52 pm    Post subject: Reply with quote

This problem is in the second point I wrote down. But a clarifying example is the Moon. The Moon's nodes move in 18.6 years through the whole ecliptic. In 2006 the NorthNode was near 0°. So highest latitude 5° occurred around 0° thus +28.5 extremes (and -28.5 minima in Capricorn). As the N-Node moves to 0°Libra in 2015 the effect is 'flattened'. 23.5-5 =18.5 maximum around 0° Cancer (-18.5 in Capricorn).

Same occurs with your Jupiter example but since his nodes move much slower you will have to wait many centuries or millennia (don't know at the moment) to get the absolute highest possible declination (and absolute minimum). With your Venus example it's the same, absolute maxima are between some 14 and 32 declination but it takes ages to see this change.

I guess that Helmut (if he's still here) will need a huge ephemeris Smile .


Last edited by Eddy on Tue Mar 30, 2010 2:13 pm; edited 1 time in total
Back to top
View user's profile Send private message
Deb
Administrator


Joined: 11 Oct 2003
Posts: 3917
Location: England

Posted: Tue Mar 30, 2010 2:04 pm    Post subject: Reply with quote

Quote:
So highest latitude 5° occurred around 0° thus +28.5 extremes (and -28.5 minima in Capricorn).


My way of reckoning this would have identified 28°43N and 28°41S as the maximum declination for the Moon. (Based on the fact that traditional texts tell us it doesn't go above 5°17N of the ecliptic or 5°12 S of it). So this is correct, yes? It doesn't mean that it regularly goes to that declination, it only points out the maximum reach.

However, if you are saying that Venus reaches 42° declination then clearly my theory fails. If you have a date for that, I'll knock the nail in the coffin.
Back to top
View user's profile Send private message
Eddy



Joined: 04 Feb 2009
Posts: 922
Location: Netherlands

Posted: Tue Mar 30, 2010 2:19 pm    Post subject: Reply with quote

Deb wrote:
My way of reckoning this would have identified 28°43N and 28°41S as the maximum declination for the Moon. (Based on the fact that traditional texts tell us it doesn't go above 5°17N of the ecliptic or 5°12 S of it). So this is correct, yes?
I used the rounded off numbers of 5° but the mean obliquity of the Moon is about 5°09' I believe and osculates between some 0°08'north and south of it. This is because of the time of the draconic year in which this depends whether the nodes are directed to the Sun or not. I'll have to look that up at home.

Quote:
However, if you are saying that Venus reaches 42° declination then clearly my theory fails. If you have a date for that, I'll knock the nail in the coffin.
Oops I made a mistake I meant 32° ( 23.5 + and - 9 ) I corrected it. You don't have to knock that nail now Smile.
Back to top
View user's profile Send private message
Deb
Administrator


Joined: 11 Oct 2003
Posts: 3917
Location: England

Posted: Tue Mar 30, 2010 2:41 pm    Post subject: Reply with quote

Ah - hope revives Smile

OK, so it seems to me that you are arguing for a degree of precision that I'm not too concerned about - since I'd quite happily round this up to the nearest degree anyway. The beauty of your approach is that it is precise, the beauty of my approach is that any old fool with a knowledge of the obliquity of the ecliptic and a traditional textbook to hand can work out the limits in a jiffy. All the bits inbetween the limits - I'm going to leave them to you Smile
Back to top
View user's profile Send private message
Eddy



Joined: 04 Feb 2009
Posts: 922
Location: Netherlands

Posted: Tue Mar 30, 2010 6:28 pm    Post subject: Reply with quote

Thanks Deb. I have to point out that I made a mistake in the use of terminology. Obliquity is the angle between a planet's equator and its orbit. I used it several places where I should have written inclination, which is the angle between orbits. The only place where I used the word properly was in the phrase "The mean obliquity of the ecliptic is now ca. 23°26' ". In all my other sentences when you see obliquity read inclination. The only place where you used the wrong terminology was just after you had read mine this was when you referred to my phrase "The "obliquity" of 3.395° which you refer to...". I guess I was a bit in a hurry this afternoon, it was while I was working at my job Secret . I hope this didn't lead to any confusion Embarassed .
Back to top
View user's profile Send private message
Martin Lewicki



Joined: 23 Mar 2007
Posts: 46

Posted: Wed Mar 31, 2010 2:07 pm    Post subject: Reply with quote

Hi all

Perhaps this illustration would help (angles exaggerated for clarity).




Edit (2010-04-01) Image updated

Martin


Last edited by Martin Lewicki on Thu Apr 01, 2010 3:24 am; edited 1 time in total
Back to top
View user's profile Send private message Visit poster's website
Deb
Administrator


Joined: 11 Oct 2003
Posts: 3917
Location: England

Posted: Wed Mar 31, 2010 2:12 pm    Post subject: Reply with quote

Ah Martin - your picture is worth a thousand words.
Back to top
View user's profile Send private message
Eddy



Joined: 04 Feb 2009
Posts: 922
Location: Netherlands

Posted: Wed Mar 31, 2010 6:48 pm    Post subject: Reply with quote

Yes that's it. It looks great Martin Thumbs up . If I only could make pictures like that, it would be of much help.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    Forum Index -> Philosophy & Science All times are GMT
Goto page 1, 2  Next
Page 1 of 2

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
. Powered by phpBB © 2001, 2005 phpBB Group

       
Contact Deborah Houlding  | terms and conditions  
All rights on all text and images reserved. Reproduction by any means is not permitted without the express
agreement of Deborah Houlding or in the case of articles by guest astrologers, the copyright owner indictated