<p>If you find it inconvenient or infeasible to code a solution for  this problem, then a semi-manual approach may be attractive.</p>
<p>Traditionally a problem like this would be addressed from the slowest (known) planet inwards (Saturn, for your stated period from BC 5500-500).</p>
<p>Once you have fixed on a piece of ephemeris software to give you planetary ecliptic positions for any desired date (maybe Aldo Vitagliano's Solex?) first find the series of time-slices, about 29.5 yr apart, when Saturn was within your target range. There must be roughly 170 of these within your period, but most can be eliminated almost at first sight because Jupiter will be nowhere near the target area: its cycle with Saturn takes close to 20 years.  The main factors that make target date-ranges hard to search automatically with precision include the irregularities due to retrogradations and orbital eccentricity, and (in your version of the problem) the elimination of the allowance for precession if that can't be automatically excluded in the software settings.</p>
<p>Once you have narrowed down to the fewer time-slices when both Saturn and Jupiter are within your range, you can make the next round of eliminations by reference to the positions of Mars within the time-slices still in play, eliminating those when Mars is not in your target area. Then look likewise among the surviving time-slices for Venus, Mercury and the Sun, and finally for the moon.</p>
<p>Results for the ancient end of your time-range will have considerable  uncertainty for the moon because of the uncertainty at those epochs of DeltaT, the difference between mean solar and dynamical time.</p>
<p>To start you off, my quick and dirty calculations indicate that the two most recent time-ranges within your time-period when Saturn was within your target range fell in about (years) -506 and -536, but both these can immediately be eliminated since Jupiter was nowhere near. And so on.
I hope that may help.</p>

CC BY-SA 4.0
2022-07-04T10:18:19.800Z
@uhoh : ok, I modified the opening sentence to avoid reflection on the utility of relevant software tools!
terry-s
CC BY-SA 4.0
2022-07-04T10:44:38.127Z
Actually maybe you went too far! :-) Unless I'm mistaken a planet will reach a given ecliptic longitude (within a few degrees) regularly at the [synodic period](https://en.wikipedia.org/wiki/Orbital_period#:~:text=The%20synodic%20period%20is). So even for the computer jockeys using Horizons or Skyfield or something else, the synodic period gives the starting point for a refined search.
uhoh
CC BY-SA 4.0
2022-07-04T12:07:15.020Z
@uhoh I think you'll find the synodic period is a ~repeat period for an object's distances from the sun, not wrt stars or equinox. The OP's problem is somewhat more involved.  I did happily take back my original opening statement, but I don't yet see anyone else coming up with an  algorithm that addresses the OP's problem in a more automated way than the semi-manual procedure with ephemeris program :):)
terry-s
CC BY-SA 4.0
2022-07-03T03:19:37.413Z
2022-07-04T10:15:55.410Z
2022-07-04T10:15:55.410Z
terry-s
<p>Let's say we have a planetary ecliptic longitudes of an unknown period.</p>
<p>What program or software or procedure can one use to arrive at the range of time periods where the planets were in those ecliptic longitudes?</p>
<hr />
<p>Basically I'm mainly looking for a time period for conjunction of Sun, Moon, Mercury, Venus , Mars, Jupiter and Saturn around 22 Deg from of J2000 vernal equniox, with a range of 8 Deg on either side. So all the planets must be within 14 Deg to 30 Deg from J2000 equinox. If 8 Deg is too narrow, we can at maximum try for 14 Deg range, so from 8Deg to 36 Deg.</p>

CC BY-SA 4.0
2022-07-03T15:51:53.533Z
Comments are not for extended discussion; this conversation has been [moved to chat](https://chat.stackexchange.com/rooms/137500/discussion-on-question-by-optimus-how-can-i-retro-search-for-time-periods-with-s).
Connor Garcia
<planetary-transits><ephemeris>
How can I retro search for time periods with specific planetary alignments?
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# How can I retro search for time periods with specific planetary alignments?

(Asked by: username_0 on 2022-07-02)

Let's say we have a planetary ecliptic longitudes of an unknown period.

What program or software or procedure can one use to arrive at the range of time periods where the planets were in those ecliptic longitudes?

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Basically I'm mainly looking for a time period for conjunction of Sun, Moon, Mercury, Venus , Mars, Jupiter and Saturn around 22 Deg from of J2000 vernal equniox, with a range of 8 Deg on either side. So all the planets must be within 14 Deg to 30 Deg from J2000 equinox. If 8 Deg is too narrow, we can at maximum try for 14 Deg range, so from 8Deg to 36 Deg.

**Tags:** planetary-transits, ephemeris
> **Comments:**
> **username_1**: Comments are not for extended discussion; this conversation has been [moved to chat](https://chat.stackexchange.com/rooms/137500/discussion-on-question-by-optimus-how-can-i-retro-search-for-time-periods-with-s).  

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## 1 answers

### Answer by username_2 on 2022-07-03. Score: 3

If you find it inconvenient or infeasible to code a solution for this problem, then a semi-manual approach may be attractive.

Traditionally a problem like this would be addressed from the slowest (known) planet inwards (Saturn, for your stated period from BC 5500-500).

Once you have fixed on a piece of ephemeris software to give you planetary ecliptic positions for any desired date (maybe Aldo Vitagliano's Solex?) first find the series of time-slices, about 29.5 yr apart, when Saturn was within your target range. There must be roughly 170 of these within your period, but most can be eliminated almost at first sight because Jupiter will be nowhere near the target area: its cycle with Saturn takes close to 20 years. The main factors that make target date-ranges hard to search automatically with precision include the irregularities due to retrogradations and orbital eccentricity, and (in your version of the problem) the elimination of the allowance for precession if that can't be automatically excluded in the software settings.

Once you have narrowed down to the fewer time-slices when both Saturn and Jupiter are within your range, you can make the next round of eliminations by reference to the positions of Mars within the time-slices still in play, eliminating those when Mars is not in your target area. Then look likewise among the surviving time-slices for Venus, Mercury and the Sun, and finally for the moon.

Results for the ancient end of your time-range will have considerable uncertainty for the moon because of the uncertainty at those epochs of DeltaT, the difference between mean solar and dynamical time.

To start you off, my quick and dirty calculations indicate that the two most recent time-ranges within your time-period when Saturn was within your target range fell in about (years) -506 and -536, but both these can immediately be eliminated since Jupiter was nowhere near. And so on.
I hope that may help.

> **Comments:**
> **username_2**: @uhoh : ok, I modified the opening sentence to avoid reflection on the utility of relevant software tools!  
> **username_3**: Actually maybe you went too far! :-) Unless I'm mistaken a planet will reach a given ecliptic longitude (within a few degrees) regularly at the [synodic period](https://en.wikipedia.org/wiki/Orbital_period#:~:text=The%20synodic%20period%20is). So even for the computer jockeys using Horizons or Skyfield or something else, the synodic period gives the starting point for a refined search.  
> **username_2**: @uhoh I think you'll find the synodic period is a ~repeat period for an object's distances from the sun, not wrt stars or equinox. The OP's problem is somewhat more involved.  I did happily take back my original opening statement, but I don't yet see anyone else coming up with an  algorithm that addresses the OP's problem in a more automated way than the semi-manual procedure with ephemeris program :):)  

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