Early Theories of Earth's Origin
The concept of Earth's origin has intrigued thinkers for centuries, leading to various hypotheses. German philosopher Immanuel Kant proposed the Nebular Hypothesis, which mathematician Laplace later refined in 1796, suggesting that planets formed from a rotating cloud of gas surrounding a young sun. Otto Schmidt and Carl Weizsäcker expanded on this in 1950, proposing that solar nebulae, rich in hydrogen and helium along with dust, eventually became dense enough to form planets through accretion.
However, moving beyond Earth, scientists began to investigate the universe's origins, leading to the Big Bang Theory. In the 1920s, Edwin Hubble observed that galaxies are moving away from each other, supporting this idea. The Big Bang Theory posits that the universe began from a singular point approximately 13.7 billion years ago, expanding and cooling over time, giving rise to matter, galaxies, and eventually, stars and planets.
The formation of stars occurs within large clouds of gas, or nebulae, where clumps of gas condense due to gravity. Through the processes of gravitational attraction and accretion, these clumps evolve into stars and planets over billions of years. This section sets the stage for understanding not just our planet's history, but the broader cosmic narrative of formation and evolution.