As Our Solar System Began to Come Together, the Sun Formed Within a Cloud of Dust and Gas

As our solar system began to come together, the sun formed within a cloud of dust and gas that continued to shrink in upon itself by its own gravitational forces.

The Earth went through a period of catastrophic and intense formation during its earliest beginnings 4.6-4.4 billion years ago. By 3.8 to 4.1 billion years ago, Earth had become a planet with an atmosphere (not like our atmosphere today) and an ocean. This period of Earth’s formation is referred to as thepre-Cambrian Period. The pre-Cambrian is divided into three parts: theHadean,ArcheanandProterozoicPeriods.

The Earth formed under so much heat and pressure that it formed as a molten planet. For nearly the first billion years of formation (4.5 to 3.8 billion years ago) — called the Hadean Period (or hellish period) — Earth was bombarded continuously by the remnants of the dust and debris — like asteroids, meteors and comets — until it formed into a solid sphere, pulled into orbit around the sun and began to cool down.

Earth's early atmosphere most likely resembled that of Jupiter's atmosphere, which contains hydrogen, helium, methane and ammonia, and is poisonous to humans. (Photo: NASA, from Voyager 1)

As Earth began to take solid form, it had no free oxygen in its atmosphere. It was so hot that the water droplets in its atmosphere could not settle to form surface water or ice. Itsfirst atmospherewas also so poisonous, comprised of helium and hydrogen, that nothing would have been able to survive.

Earth’s second atmospherewas formed mostly from the out gassing of such volatile compounds as water vapor, carbon monoxide, methane, ammonia, nitrogen, carbon dioxide, nitrogen, hydrochloric acid and sulfur produced by the constant volcanic eruptions that besieged the Earth. It had no free oxygen.

About 4.1 billion years ago, the Earth’s surface — or crust — began to cool and stabilize, creating the solid surface with its rocky terrain. Clouds formed as the Earth began to cool, producing enormous volumes of rainwater that formed the oceans. For the next 1.3 billion years (3.8 to 2.5 billion years ago), the Archean Period, first life began to appear and the world’s landmasses began to form.Earth’s initial life formswere bacteria, which could survive in the highly toxic atmosphere that existed during this time.

Toward the end of theArchean Periodand at the beginning of theProterozoic Period, about 2.5 billion years ago, oxygen-forming photosynthesis began to occur. The first fossils were a type ofblue-green algaethat could photosynthesize.