What is the birth of Earth? (1)
The birth of Earth refers to the formation of our planet approximately 4.5 billion years ago, a process that took place within the context of the formation of the Solar System. Here’s an overview of how Earth came into existence:
1. Formation of the Solar System (about 4.6 billion years ago)
- The story of Earth’s formation begins with the birth of the Solar System, which occurred from a solar nebula, a giant rotating cloud of gas and dust, primarily composed of hydrogen and helium, along with heavier elements.
- Under the influence of gravity, this nebula began to collapse and spin faster. At its center, a dense region formed, eventually igniting nuclear fusion to become the Sun. The remaining material flattened into a disk around the Sun, which began the process of planet formation.
2. Accretion of Planetary Material
- In the protoplanetary disk surrounding the young Sun, dust and gas particles started to stick together due to electrostatic forces, forming small clumps.
- These small clumps collided and merged, forming larger bodies called planetesimals. Over time, as these planetesimals continued to collide and grow, they formed protoplanets, which were the early precursors to planets.
3. Formation of Earth (about 4.5 billion years ago)
- Earth formed through a process known as accretion, where planetesimals and other debris in the inner solar system collided and coalesced into a larger body.
- Gravitational compression and the kinetic energy of collisions heated this early Earth, causing it to be molten in its early stages. Over time, the heavier elements, such as iron and nickel, sank to form the core, while lighter materials formed the mantle and crust. This differentiation created Earth’s layered structure.
4. The Formation of the Moon (about 4.5 billion years ago)
- Shortly after Earth formed, it is believed that a Mars-sized object (often called Theia) collided with the early Earth. This massive impact ejected a significant amount of debris into space.
- This debris eventually coalesced to form the Moon. The impact also contributed to Earth’s tilted axis, which is responsible for the planet’s seasons.
(To be continued)