New simulations reveal the Moon's birth may have occurred in just 24-36 hours due to a collision with Theia, with temperature differences shaping its formation.
Collision theory revisited
A widely accepted theory in astrophysics suggests the Moon formed from a violent collision between the early Earth and a Mars-sized object called Theia. Recent research, published in The Astrophysical Journal Letters, has re-examined this theory using advanced simulations that consider the geological structures of both the young Earth and Theia.Modeling the collision
The simulations used a method called smoothed particle hydrodynamics, which is used to model the movement of fluids by treating them as a collection of particles. This technique is commonly used in astrophysics to study phenomena such as galaxy formation and star collisions.Parameters of the impact
Researchers tested different factors to make the collision more realistic, including the resistance to deformation, surface temperatures, and the angle and speed of impact. Theia’s temperature was tested at three values: 400, 800, and 2,000 degrees. The models showed the Moon could form in 24 to 36 hours, with Theia’s temperature playing a crucial role.Theia’s temperature impact
Erik Asphaug, a planetary scientist and co-author of the study, explains that Theia’s thermal structure is important. If Theia was 400 degrees, a debris disk would form. At 2,000 degrees, the Moon would form directly and intact. A temperature of 800 degrees would lead to a partially intact Moon.Formation time scales
Asphaug notes that if the Moon forms directly, it must happen within a few hours, driven by gravitational forces. However, if a debris disk forms, the Moon would take much longer to coalesce from that material, possibly hundreds of thousands of years after the initial collision.Alternative theories and future research
Other theories for the Moon’s formation include multiple collisions or capturing a piece of Theia. These have not considered the internal structure of the colliding bodies. Future research may explore how the Moon’s formation affected other planets, such as Venus and Mars, and how debris was removed from the system.
