It is convenient to draw planet configuration with following data.

Revolution of planetsEdit

Table of synodic periods in the Solar System, relative to Earth:

    Sid. P. (a)   Syn. P. (a)   Syn. P. (d)
Mercury       0.241   0.317   115.9
Venus       0.615   1.599   583.9
Earth       1     —     —
Moon       0.0748     0.0809   29.5306
Mars       1.881   2.135   780.0
4 Vesta       3.629   1.380   504.0
1 Ceres       4.600   1.278   466.7
10 Hygiea       5.557   1.219   445.4
Jupiter       11.87   1.092   398.9
Saturn       29.45   1.035   378.1
Uranus       84.07   1.012   369.7
Neptune       164.9   1.006   367.5
134340 Pluto       248.1   1.004   366.7
136199 Eris       557   1.002   365.9
90377 Sedna       12050   1.00001   365.1

Superior and inferiorEdit

Positional astronomy

As seen from a planet that is superior, if an inferior planet is on the opposite side of the Sun, it is in superior conjunction with the Sun. An inferior conjunction occurs when the two planets lie in a line on the same side of the Sun. In an inferior conjunction, the superior planet is "in opposition" to the Sun as seen from the inferior planet.

The terms "inferior conjunction" and "superior conjunction" are used in particular for the planets Mercury and Venus, which are inferior planets as seen from the Earth. However, this definition can be applied to any pair of planets, as seen from the one further from the Sun.

A planet (or asteroid or comet) is simply said to be in conjunction, when it is in conjunction with the Sun, as seen from the Earth. The Moon is in conjunction with the Sun at New Moon (or rather Dark Moon).

"Quasi-conjunctions" are also possible; in this scenario, a planet in retrograde motion — always either Mercury or Venus — will "drop back" in right ascension until it almost allows another planet to overtake it, but then the former planet will resume its forward motion and thereafter appear to draw away from it again. This will occur in the morning sky, before dawn; or the reverse may happen in the evening sky after dusk, with Mercury or Venus entering retrograde motion just as it is about to overtake another planet (often Mercury and Venus are both of the planets involved, and when this situation arises they may remain in very close visual proximity for several days or even longer). The quasi-conjunction is reckoned as occurring at the time the distance in right ascension between the two planets is smallest, even though, when declination is taken into account, they may appear closer together shortly before or after this.

See alsoEdit

External linkEdit

Earthquake prediction by geometric relationship of planets, moon, and sun.