The Big Bang is indeed believed to have primarily produced hydrogen and helium, along with trace amounts of lithium and beryllium. The formation of planets, including Earth and gas giants like Jupiter, involves subsequent processes that occurred over billions of years.
After the Big Bang, the universe consisted mostly of hydrogen and helium gas, but it also contained tiny density fluctuations and variations in temperature. These fluctuations served as seeds for the formation of structures like galaxies, stars, and planets through a process called cosmic evolution.
Here's a simplified overview of how planets form:
Galaxy Formation: Over time, gravity caused the hydrogen and helium gas to come together, forming vast clouds or nebulae. These clouds continued to collapse under their own gravity, leading to the formation of galaxies. Within galaxies, regions of higher density, called molecular clouds, began to form.
Protostar Formation: Within molecular clouds, regions with higher density and mass continued to collapse, forming protostars. These protostars are the precursors to stars, and their formation involved the conversion of gravitational potential energy into thermal energy.
Accretion and Protoplanetary Disk: As the protostar formed, the surrounding material began to flatten into a rotating disk called a protoplanetary disk. This disk consisted of gas, dust, and other solid particles. Over time, these particles collided and stuck together through a process called accretion, gradually growing larger.
Planetesimal Formation: The accretion process continued, and the solid particles in the protoplanetary disk eventually became planetesimals. These are kilometer-sized objects composed of rock, metal, and ice.
Planet Formation: Planetesimals continued to collide and merge, gradually forming larger bodies known as protoplanets. The protoplanets eventually grew into fully formed planets through further accretion and gravitational interactions.
For planets like Earth, the process involved the accumulation of a mixture of rock, metal, and ice. Gas giants like Jupiter also began with a solid core but then went through a process called gas accretion, where they accumulated large amounts of hydrogen and helium gas from the surrounding disk.
It's important to note that these processes took billions of years to unfold and were influenced by various factors, including the composition of the protoplanetary disk, the distance from the star, and interactions with other objects in the system.
In summary, while the Big Bang primarily produced hydrogen and helium, subsequent cosmic evolution processes, such as star formation and the accretion of materials in protoplanetary disks, led to the formation of planets like Earth and gas giants like Jupiter.