In particular, a planet around a star can undergo chaotic motion if a perturbation, such as another large planet, is present.

One is that the planet underwent some sort of atmospheric change.

"It appears that this planet is undergoing a period of major glaciation," Data spoke up.

But since those times the planet has undergone a unique shrinkage.

For the case of Venus no seasonal lag would be detected, because the planet undergoes no seasons.

Possibly the planet is undergoing natural gravitational stresses.

"This planet has obviously undergone some kind of destabilization recently," the fellow who had boarded the Condor said.

The weather that the planet is undergoing is only compounding the problem of offworld vessels stacking up outside the atmosphere.

This planet has undergone major geologic upheaval since it was formed.

Given the changes our planet is undergoing, we need collective courage to meet these ecological challenges.