But because there may be either one or two transits at each node, other intervals are possible; for instance when series B ends there will be just one transit at the ascending node giving the sequence 129 1/2, 8 and 105 1/2 years.
In the distant future other intervals may be possible, and in any event, by then the paths of successive transits occurring at the ascending node will already be shifting northward.
First we again derive the right ascension [OMEGA] of the ascending node
, the inclination I of the orbit, and both arguments of declination [u.
While the Moon closets itself in the Earth's shadow at the ascending node of its orbit this month, the Sun is occupying the descending node on the opposite side of the sky in Pisces, the Fishes.
When the Moon eclipsed the Sun last October 24th, Spica in Virgo was west (right) of the Moon, the Sun, and the ascending node.
Levison and Stern claim Pluto avoided this fate because something knocked it solidly into the orbital resonance, in such a way that its perihelion and ascending node
remained far apart as well.
The "splash" points, where the fish enters and leaves the water, are, respectively, the descending and ascending nodes
-- points where the Moon passes through the Earth's orbital plane.