Which of the following discoveries would cause us to re-evaluate the nebular theory for forming planets?
A) A star's 5 terrestrial planets orbit in the opposite direction of its 3 jovian planets.
B) Of the star's five terrestrial planets, one has a large moon.
C) Two of the star's planets are rotating in directions backwards compared to their orbital direction.
D) A star has 20 planets.
E) A star has zero planets.

Question

Quizplus · Accepted Answer

The nebular theory predicts that all planets in a given planetary system should orbit the same direction as their parent star. If a star is found to have planets orbiting in opposite directions, it would indicate that either the nebula from which the system formed was disrupted, or the interacting gravitational forces among planets have caused them to re-orient their orbits over time.

Which of the Following Discoveries Would Cause Us to Re-Evaluate