(collision of one solid body with another)
In astronomy, impact generally refers to the collision of two
solid bodies, possibly both of significant size, or possibly one
much smaller than the other. Craters are evidence of impacts.
Impacts are assumed in theories of planet formation, both to
explain how planets grew, assuming one of the bodies gained the
material from the other, and how bodies came to have their constituents,
assuming impacts removed the outer surface removed by one or more
impacts (impact erosion), which can leave the body denser if the
densest material had already fallen toward the center of the body.
It is assumed both scenarios occur, depending upon the velocity
of the impact(s).
The favored theory of the Moon's formation is that it results from
a giant impact, the impact of a Mars-sized planet with
Earth (known as the giant-impact hypothesis).
Referenced by pages:
globular cluster (GC)
GW detection (GW)
late heavy bombardment (LHB)
maximum iron fraction
minimum orbit intersection distance (MOID)
near-Earth object (NEO)
smoothed-particle hydrodynamics (SPH)