AUGUST 2005 

Periodically Pluto’s and Neptune’s orbits overlap. Why don’t they bang into each other? I found this explanation of their orbital relationship.

Neptune’s orbit is more or less circular, and lies in the ecliptic plane with the other planets. Pluto’s orbit is very elliptical, and has its own plane, quite different from the other planets. Their resonance is regular. Pluto orbits the Sun twice for every three orbits of Neptune. This, together with the different orbital planes, keeps the planets always far apart.

This resonance has kept Pluto from being ejected from the solar system by Neptune’s gravity during the past 4.5 billion years.

Speaking of the outer solar system, a new solar system planet has been discovered, outside of Pluto and larger than Pluto. It is temporarily called 2003 UB313. It is thought to have a 560-year erratic orbit.

Aha! Transpluto! I thought. My Transpluto book is filled with calculations delineating Transpluto, as well as various astronomer’s descriptions of its characteristics. They all agree that it has a 677-685 year orbit, a bit slower than UB313.

There is literally much happening in the outer solar system. It is another whole universe, mysterious and fascinating.