The Moment of Impact
The collision of the Moon with Earth would initiate with an immense release of kinetic energy. The Moon, traveling at orbital velocities, would strike the Earth with energy equivalent to trillions of megatons of TNT. This energy would instantly vaporize vast amounts of material from both celestial bodies at contact. The initial impact site would become a superheated plasma, expanding rapidly outwards.
Upon impact, a crater, thousands of kilometers in diameter, would form, displacing Earth’s crust and mantle. Shockwaves would propagate through the planet’s interior, causing the globe to reverberate. Temperatures at the impact site would reach millions of degrees Celsius, sufficient to melt and vaporize rock and metal.
The collision would deform and fracture Earth’s crust globally. Material from both the Moon and Earth would be ejected into space and the atmosphere at high velocities.
Global Environmental Disruption
Following the direct impact, ejecta—vaporized rock, dust, and debris—would be launched into Earth’s atmosphere. This blanket would rapidly encircle the globe, obscuring the sun and plunging the planet into profound darkness. The blockage of sunlight would trigger an immediate “impact winter,” causing global temperatures to plummet.
As ejected material re-entered the atmosphere, friction would generate intense heat, igniting widespread global firestorms. These fires would consume vast swaths of vegetation, contributing to atmospheric opacity and releasing soot and carbon dioxide.
The atmosphere’s composition would change dramatically, as superheated steam from vaporized oceans and noxious gases from burning biomass mixed with pulverized rock. This new atmospheric cocktail would be largely unbreathable and corrosive. The sustained lack of sunlight, extreme temperature fluctuations, and atmospheric pollution would render the surface environment uninhabitable for complex life.
Reshaping Earth’s Surface
The impact would generate seismic waves of unprecedented magnitude, far surpassing any known earthquake. These shockwaves would travel through the entire planet, causing Earth’s crust to heave and fracture globally. This immense seismic activity would trigger widespread earthquakes across all continents, devastating existing landforms.
Oceanic regions affected by the collision would experience the displacement of water, generating mega-tsunamis. These towering waves, thousands of meters high, would surge across ocean basins, inundating coastal areas and sweeping far inland. The energy transferred to the oceans would reshape coastlines and alter bathymetry.
Stress on Earth’s lithosphere would trigger widespread volcanic eruptions and increased tectonic activity. New rift zones could form, and existing volcanoes would erupt with renewed intensity, altering the planet’s surface with lava flows and ashfall. The combined geological forces would result in a fundamentally transformed landscape, marked by new mountain ranges, vast impact basins, and altered ocean depths.
A Transformed Planet
The complete loss of the Moon would fundamentally alter Earth’s astronomical characteristics and long-term stability. Earth would lose the Moon’s stabilizing gravitational influence, which currently helps maintain a relatively stable axial tilt. Without this lunar effect, Earth’s axial tilt could fluctuate more dramatically over geological timescales, leading to extreme climatic shifts in the distant future.
The cessation of the Moon’s gravitational pull would also eliminate tidal forces, which currently drive ocean tides and influence geological processes. The absence of tidal friction would likely affect Earth’s rotation, potentially altering the length of a day, though the immediate impact would be overshadowed by the collision’s energy. Earth would become a solitary planet without its large natural satellite.
The long-term implications for life would be profound, even if any life survived the initial catastrophe. The drastically altered environment, including a potentially unstable axis, a changed rotation, and a surface scarred by impact and geological upheaval, would present a completely new evolutionary landscape. Any future life would adapt to a world profoundly different from the one we know today.