Explanation of Terms


This discussion will exclude some of the considerations needed in order to be perfectly accurate regarding the referred to celestial events, but my current level of understanding prohibits being perfectly accurate. Hopefully, I will be able to explain the situations sufficiently for our purposes here -- without including the excluded considerations...

1. Each of the planetary orbits in our solar system occupies essentially the same plane as do the others -- but not quite.

2. The time the planets require to orbit the sun varies quite a bit between planets.
3. Naturally, the planets closer to the sun take much less time to orbit the sun than do the more distant planets.
4. For instance, while Mercury takes approximately 88 earth days to orbit the sun, Uranus takes approximately 84 earth YEARS.
5. Consequently, were we able to observe the planets from the sun, we'd see Mercury "pass" Uranus about once every 89 days...
6. Not being in quite the same plane, most of the "passes" would not involve an "eclipse," or "occultation" -- we'd be able to see the more distant planet during the passing.

7. A "conjunction" occurs during this passing -- specifically, it occurs when one planet is directly above, below or behind the other planet.
8. In other words, technically speaking, a conjunction between two planets occurs when they are at the same celestial "longitude," or "meridian," as seen from the observer's perspective. (There's another "kind" of celestial conjunction, but trying to describe it now is currently unnecessary -- hopefully -- and virtually impossible.)

9. Also because the planes of the different orbits are not quite the same, the perceived separation between the two planets involved in the conjunction would vary quite a bit between each pass.
10. Calculating the conjunctions as seen from the sun is difficult enough, but calculating the conjunctions as seen from the earth is much more difficult because we have our own orbit and plane to include in the mix…

11. There are also conjunctions between planets and stars.

12. Also, due to our own orbit, there is what astronomers call "retrograde motion" within the starry field...
13. As seen from the sun, due to their orbits, all the planets slowly move to the "left" through the starry field at a constant speed. In reference to the starry field, we on earth would see them moving slowly to the east
14. As seen from the sun, the earth takes approximately 365 days to move through the entire starry field, and start all over again.
15. But the starry field it actually moves "through" is limited to those stars and constellations that basically occupy the plane of our own orbit.
16. As seen from the sun, the Earth does not move through the starry field occupied by the North Star, for instance (except, in a sense, for every 2000 years, I think…).

17. Anyway, as seen from the Earth, the perceived movement of Jupiter through the starry field would occupy much the same plane as it would from the sun, but the speed of its movement through the field would be irregular. Sometimes, Jupiter would speed up in this movement; sometimes, it would slow down; sometimes, it would stop.
18. This irregularity is caused by the fact that the Earth is orbiting the sun itself, and taking a shorter time to orbit than is Jupiter –which means that for a while the angle between the line drawn between Earth and Jupiter and that drawn between Earth and (say) Regulus increases, but slows down in its increasing and eventually starts decreasing.
19. This is responsible for what is called “retrograde motion,” and allows the earth to start moving backwards relative to Regulus for a time. (Not to worry, I don’t REALLY understand this either.)
20. When we’re in the right cycle, Jupiter’s retrograde motion will cause a “triple” conjunction. Regulus “passes” Jupiter; Jupiter speeds up for awhile and passes Regulus; but then, Jupiter can’t maintain its perceived speed and gets passed again. This doesn’t happen too often.
21. To ancient Astronomer/Astrologers, conjunctions were very meaningful.

22. When Jupiter perceptually stops relative to Regulus and the starry field, Astronomers say that Jupiter is in “station.”