(a link to your search results will appear here)

Need help? Form not working? Read the notes, or email astro@barrycarter.info

Conjunctions database search form
Planet 1
The first conjuncting planet, the one closer to the Sun (use "any planet" to see all conjunctions; Uranus is not on this list, since it can never be the nearer planet)
Planet 2
The second conjuncting planet, the one farther from the Sun (use "any planet" to see all conjunctions; Mercury is not on the list, since it can never be the farther planet).
Years to
The years for which you want to see conjunctions. This database covers conjunctions from the years -13200 to 17190.
Separation
The maximum angular separation between the two conjuncting planets. This database contains conjunctions up to 6 degrees apart (so setting this value higher than 6 won't give you more results, but setting it lower than 6 will give you fewer results)
Solar Distance
The minimum distance from the Sun for this conjunction. Conjunctions close to the Sun are difficult to see, since they occur during twilight. Use '0' to see all conjunctions, regardless of how close they are to the Sun.

Notes

This form provides limited access to the conjunctions table, which lists conjunctions of the visible planets (Mercury, Venus, Mars, Jupiter, Saturn, and Uranus) from -13200 to 17190 (which are the limiting times for which NASA provides planetary position information).

Some of the "cooler" conjunctions I found are here.

To search for all conjunctions involving Mars (for example), first run a query choosing Mars as Planet 1 and setting Planet 2 to "Any Planet". This will find when Mars conjuncts Jupiter, Saturn, or Uranus.

Then, run a second query, choosing Mars as Planet 2 and setting Planet 1 to "Any Planet". This will find when Mars conjuncts Mercury or Venus.

Of course, if you're accessing the table directly, you can use "'Mars' in (p1,p2,p3,p4,p5,p6)" (for example). If you're pedantic, "'Mars' IN (p1,p2,p3)" suffices, since Mars can never be more than the 3rd furthest planet in a conjunction of visible planets.

If you know SQL well, you can access the full database at http://astro.db.mysql.barrycarter.info/. The database has no instructions, so, if you don't know SQL (MySQL engine) well, this won't be very useful.

When you click "view results", the bottom of the results page will show the query that created your results. If you know SQL moderately well, you can modify this query to refine your results.

The default search is limited to 200 rows. You can remove this limitation on the results page by removing "LIMIT 200" from the query. However...

Queries are limited to 5 seconds of CPU time (which can be more than 5 seconds of clock time). If your results time out repeatedly (or you run into any other problems), please feel free to contact me at astro@barrycarter.info

A list of all 454,981 conjunctions is available at http://test.barrycarter.info/ASTRO/. This file is 23.9M compressed, and 91.0M uncompressed.

Note that any conjunction of 4 planets (eg, Venus, Mars, Jupiter, Uranus) will also be listed as four conjunctions of 3 planets (ie, Venus-Mars-Jupiter, Venus-Mars-Uranus, Venus-Jupiter-Uranus, Mars-Jupiter-Uranus), and as 6 conjunctions of 2 planets (Venus-Mars, Venus-Jupiter, Venus-Uranus, Mars-Jupiter, Mars-Uranus, Jupiter-Uranus).

There will be similar multiple conjunctions when 3, 5, or 6 planets conjunct. For example, a conjunction of all 6 planets (which only occurs once) also yields 5 5-planet conjunctions, 15 4-planet conjunctions, 20 3-planet conjunctions, and 15 2-planet conjunctions, for a whopping total of 56 conjunctions.

Do not rely on this information. You can (and should) check this information against a planetarium program (like Stellarium) and/or NASA HORIZONS (http://ssd.jpl.nasa.gov/?horizons). Of course, neither of these is necessarily 100% accurate either. Additional disclaimers below.

I used planetary system barycenters (the center of mass of a planet and its moons) for the following reason: if you ask HORIZONS (http://ssd.jpl.nasa.gov/?horizons) for the position of Mars and set the date, you'll see this notice:

Available time span for currently selected target body: 1900-Jan-04 to 2500-Jan-04 CT.

However, if you use Mars' barycenter, this becomes:

Available time span for currently selected target body: BC 9998-Mar-20 to AD 9999-Dec-31 CT.

In other words, NASA computes the position of Mars' planetary system barycenter for a much longer interval than they compute Mars' actual position. Since I wanted to compute conjunctions for a long period of time, I went with the barycenters (DE431 computes barycenters even beyond 9998 BC and 9999 AD).

I've complained to NASA that this is silly, especially for Mars, since the distance between Mars' center and Mars' planetary system barycenter is only about 20cm (yes, centimeters, since Phobos and Deimos have very little mass) per http://naif.jpl.nasa.gov/pub/naif/generic_kernels/spk/planets/aareadme_de430-de431.txt. However, NASA apparently plans to keep it this way.

I ignore light travel time, which introduces a small error. Most planetarium programs, like Stellarium, ignore light travel time by default, although Stellarium has an option to turn it on.

I ignore things like refraction, aberration, and similar minor adjustments.

If you are using Stellarium to verify/view these conjunctions, note that Stellarium appears to have difficulty with dates before -4800 Mar 1, so you may not be able to verify conjunctions prior to this date.

The database only includes conjunctions between the visible planets (Mercury, Venus, Mars, Jupiter, Saturn, and Uranus). It does not include conjunctions/occultations/transits involving Neptune, the Moon, the Sun, the (other) stars, or any asteroids/minor planets.

The database will tell you the angular distance to the Sun, but that's not the same as including solar conjunctions or transits.

When you use the search form to query, you received a "prettified" version of the results. If you are accessing the table directly, here is a description of the fields:


p1: The first planet to conjunct. This must be the conjuncting planet
closer to the Sun.

p2: The second planet to conjunct. This must be the conjuncting planet
farther from the Sun.

p3 through p6: The third through sixth planets to conjunct, in
increasing distance from the Sun. If you're only interested in two
planet conjunctions, you can leave these fields blank. If you're
interested in three-planet conjunctions, you can leave fields p4
through p6 blank, and so on.

jd: The Julian date of the conjunction, probably useful only to techies

cdate: A prettified version of the conjunction date and time.

MySQL's DATETIME type only supports years back to 1000, so I could not
use a true DATETIME field here. The cdate field is actually text.

For searches, you should use the next four fields, which break out the
date into integer fields and the time into a simple TIME field.

year/month/day: The year, month, and day of the conjunction. As per
standard astronomical convention
(),
0 stands for the year 1BCE, -1 stands for the year 2BCE, and so on.

time: The UTC time of the conjunction

sep: The angular separation between the conjuncting planets, in
degrees. For more than two planets, this is maximum angular separation
between any pair of planets.

sunsep: The angular separation (in degrees) from the Sun of the
conjuncting planet nearest to the Sun. Conjunctions close to the Sun
can be difficult to see. Of course, Mercury (and to a lesser extent,
Venus) are always close to the Sun, so conjunctions involving these
planets will always be somewhat close to the Sun.

sjd: The Julian date for the "start" of the conjunction; in other
words, when the conjuncting planets were first within 6 degrees of
each other.

sdate: A prettified version of sjd. For searches/sorting, use sjd, not
this field.

ejd: The Julian date for the "end" of the conjunction, when the
conjuncting planets are last within 6 degrees of each other.

edate: A prettified version of ejd.

NOTE: Normally, there is only one "conjunction" for every sjd, ejd
pair. However, it's possible for 2 or more planets to come within 6
degrees of each other, approach as close as 2 degrees, move away again
to 3 degrees, then come together again to 1 degree, before finally
moving apart until they are more than 6 degrees away. In this case,
both the 2 degrees event and then 1 degree event will be listed as
"conjunctions", and will have the same sjd and ejd

Source code and notes at Github:

https://github.com/barrycarter/bcapps/tree/master/ASTRO

This database was created in part to answer:

and my answer may contain additional useful information, as may another related question: