proto-Earth

Proto-Earth refers to the early stages of Earth's formation, approximately 4.56 billion years ago, as it accreted from a cloud of gas and dust in the solar nebula. This process involved the condensation of mineral grains and the aggregation of solid material, forming planetesimals that eventually grew into larger bodies, including Earth.1

The composition of early Earth is thought to be similar to that of primitive meteorites, known as carbonaceous chondrites, which contain water. As Earth formed, its metallic core began to develop, likely causing volatile substances to escape and form an early atmosphere. This atmosphere was likely rich in water vapor, carbon dioxide, and hydrogen sulfide, with little to no oxygen. The presence of liquid water on Earth's surface, indicated by 3.85-billion-year-old marine sediments, suggests surface temperatures above 0 °C (32 °F) during this early Precambrian period.234