An Introduction to Modern Astrophysics · Problem 20.5
The Formation of Planetary Systems — Carroll & Ostlie
Physics — Astrophysics · mercury-impact-stripping
Problem
(a) From the data presented in the text, estimate the kinetic energy of the impact that may have been responsible for stripping off the outer layers of Mercury early in the history of the Solar System.
(b) If, prior to the collision, Mercury had twice as much mass as it does today, how much energy would have been required to lift that additional mass off the present planet? Assume that the extra mass had the density of Earth's present-day Moon and that the material was uniformly distributed in a spherical shell around the present-day Mercury. Don't forget to include the energy required to eject the mass of the impactor as well.
(c) Solely on the basis of energy considerations comment on the feasibility of this scenario for the origin of Mercury as we observe it today.