How long for a complete solar system cycle Considering the solar system as a closed system, how long until all the planets pass twice by the same position relative to each other? I would say that you'd have to get the length of the year in each planet and find the lowest number that can be divided by them, is that correct or are there more things to take into account?

Furthermore, can one do this also considering the moons of the planets?

Thank you!
It depends how precisely you mean the same position.

Take 2 since my previous attempt was ... optimistic.

In the late 1970's, the outer planets were moving into a configuration that made a Planetary Grand Tour much cheaper and quicker. They will be in a similar configuration in about 175 years.

But when will the planets be in the exact configuration? Never, well, not before the Sun turns into a red giant and swallows the inner planets.

But from time to time the planets will all be on the same side of the Sun. If the planets were all in a line, then after 495 years they would all be on the same side of the Sun, then again at 500 years, 522 years, 523 years (these last two are, of course 88 days apart, the period of Mercury), 995 years, 997 years, 1006, 1183 years, etc.