The orbital period of Jupiter is just under 12 years, which means that Jupiter spends roughly a year in each sign. But it’s not always exactly a year – sometimes it’s a little more, other times it is a little less, and these variations don’t occur in any predictable pattern.
Like the inner planets, Jupiter also has a periodic apparent retrograde motion that sometimes makes it alternate between signs for a few months at a time. Here is an extreme example of an interrupted journey through a sign:
Notice how choppy Jupiter’s residence is in Libra. It enters Libra a little before December 1968, sticks around a bit, then turns and goes back to Virgo in late March 1969. Then, it pushes forward again and re-enters Libra in late July 1969. It goes all the way to the end of Libra, then enters Scorpio in late December 1969.
But, wait, it’s not done with Libra yet. In very late April 1970, it retreats back into Libra, where it spends another 4 months, before finally moving forward and into Scorpio for good sometime in August of 1970.
The time spent in retrograding increases with the orbital period. So while Mercury and Venus go retrograde for two to three weeks at a time, and Mars goes retrograde for 8 to 10 weeks at a time, Jupiter goes retrograde for two to three months.
What we see in this example is one extreme situation, because the retrograde periods are at the cusps of signs, so multiple signs are caught up in the to and fro movement.
On the other extreme, Jupiter’s retrograde motion could be completely confined to one sign, in which case everyone born in an uninterrupted 10 to 12 month stretch would have the same Jupiter sign.
In any case, you will share your Jupiter sign with many more people around your age than you would share your Sun, Moon, Mercury, Venus, or Mars signs. However, differences in the sign placements of the Sun, Moon, and inner planets compared to yours will lead to significant differences in personality. Furthermore, even if Jupiter signs are the same, the interactions (what are called aspects, which I will cover in a future post) of Jupiter to the other planets will be different, leading to a different intensity and range in the personality expression of the Jupiter sign.