The leading theory is the giant impact hypothesis. A Mars-sized object hit early Earth. Debris was blasted into orbit. This material eventually formed the Moon. Chemical similarities support this idea. The impact reshaped Earth itself. Our planet’s tilt likely came from it.
This matters because it explains Earth-Moon similarities. Shared material links their histories. Origins influence evolution.
It also shows violent beginnings are common. Planetary systems form through destruction. Order emerges from chaos.
The Moon formed about 4.5 billion years ago after a colossal impact.
[NASA, nasa.gov]