Jupiter contains a number of small moons that are thought to be captured comets or material ejected by collisions with larger objects. What is the evidence for this theory?
A) Spacecraft have sampled them, and they are known to be comets.
B) Analyses from spacecraft show they have compositions completely different than Jupiter or its moons.
C) They are too big to have been formed during planetary accretion.
D) Their orbits are highly elliptical, off the plane of the ecliptic, and many are retrograde, which is unlikely for satellite formed during planetary accretion.

Question

Quizplus · Accepted Answer

The small moons of Jupiter having highly elliptical and retrograde orbit, which is unlikely for any satellite formed during planetary accretion, suggests that they were captured from elsewhere in the solar system. This provides evidence for the theory that they are captured comets or material ejected by collisions with larger objects. Option A is incorrect as spacecraft sampling is not the only way to determine the origin of the moons. Option B is incorrect as it is not necessary for the composition of the moons to be different from Jupiter or its moons, as they could have originated from a different location in the solar system. Option C is incorrect as the moons are small enough to have formed during planetary accretion.

Jupiter Contains a Number of Small Moons That Are Thought