Our Earth first came into existence 4,543,000,000 years ago as an inhospitable ball of molten rock that barely survived a crash from a Mars-sized rogue planet whose impact gave rise to the creation of our moon.
In this alternate timeline, Earth was created exactly five billion years ago as the result of a collision between two rogue planets. One was obliterated into pieces while the other was lucky to have some crust and atmosphere left.
One was similar to Venus—a hot ball of molten rock concealed by a thick atmosphere of sulfuric acid, carbon dioxide and methane. The ancient atmosphere was so thick that the pressure would be comparable to a man trying to lift the Queen Elizabeth 2, an ocean liner that weighs roughly 50,000 tons. Beneath the lava-ridden surface was a core of iron, nickel, platinum, titanium, uranium, silver and gold.
To understand the other rogue planet, we must look at one of Jupiter’s moons, Europa. Back home, it has a diameter of 1900 miles, which makes it a little smaller than our moon. But what really does make it stand out is its crust. The first ten to 30 kilometers of it—six to 19 miles—of ice. Beneath that is 160 kilometers—or 100 miles—of liquid water before descending down to a rocky, silicate mantle and finally to a core of iron and sulfur. This second rogue planet is pretty much Europa enlarged to the size of its larger brother, the moon Ganymede, a diameter of 3270 miles.
During the collision, the kinetic energy reduced one rogue planet’s icy surface and the water it might have concealed into a vast nebula of water vapor that enveloped the planet at low orbit. The majority of the gas might have escaped to space, but the pressure of the atmosphere was so high that not all of the water vapor molecules could escape.
After the collision, the two cores merged together to become a brand-new one. The largest pieces of debris clumped together to create the alternate Earth. The smallest of the debris, meanwhile, clumped together to create its moon.
The trapped water vapor cooled down, condensing into rainwater that hit on the still-molten surface, resulting in the release of steam which rose to the atmosphere, gathering more water vapor, which ultimately means more rain. For the first 250 million years after impact, this repeated cycle of evaporation and condensation would create the oceans of Great Lakes Earth.
Is this scenario likely or not?