How do nongravitational accelerations of interstellar objects compare to gravity?

• A. They are several orders of magnitude weaker than gravitational accelerations.
• B. They are stronger than gravitational accelerations.
• C. They are approximately equal to gravity.
• D. They dominate orbital dynamics.

Answer: (A)

Gravity from the star is the main force shaping the path of an interstellar object as it moves through a planetary system. Nongravitational accelerations, such as those from outgassing or solar radiation pressure, are present but tiny in comparison. At distances where planets reside, the Sun’s gravitational pull is on the order of 0.006 m/s^2, while nongravitational effects for typical bodies are around 10^-8 to 10^-6 m/s^2. That means these nongravitational forces are several orders of magnitude weaker than gravity, so they don’t drive the overall trajectory the way gravity does.