Again the answers I get as usual are circular thinking. They are not an answer. If the answers you get are ok with you then so be it but I personally prefer more definitive answers. I will quote from a text book.
The sun and planets probably formed from aggregates of dust particles and debris about 4.6 billion yrs ago. Intense heat produced by gravitational energy and radioactivity of some atoms caused the earth to become stratified into a core, a mantle and a crust. Heavier atoms of iron and nickel became the molten liquid core, and dense silicate minerals became the semiliquid mantle. The lighter molecules of silico, aluminum, and iron formed the crust.
Probably is not a science answer, it is a guess. The rest of it is making an assumption of prior existence without explaining how it originally came to be. Where did the original energy come from and how. Look up how energy is made.
Rest of paragraph says this, The temperature was so hot that atoms could not permanently bind; whenever bonds formed, they were quickly broken. Cooling had to occur before an atmosphere could develop.
Again exactly where is the explanation as to how this occurred and notice it also said cooling had to occur before the atmosphere could develop. I want more info than that. That paragraph explains NOTHING to me.
What caused cooling and where did all original stuff come from and can this be reproduced in a lab to prove the statements.
Your book is a little dated.
The sun is around 5 billion years old and the earth 4.57 billion.
The planets formed from material left over from the formation of the sun. The processes is called stellar and planetay accretion. We see stars like the sun born everyday, even new solar systems. Even the material that crated our sun and planets is material left over from earlier super nova star explosions, which is where the heavy elements are formed. So our sun and planets are recycled material.
The core of the earth is still cooling. But back then it had to cool to form the van allen belts that protect the earth from super high radation from the sun. Basically the earth is like a magnet. Also a planet the size of Mars hit the early earth and formed our moon. This was a massive impact. No life would have survived the early earth enviroment or the impact.
How the earth formed
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Earth: Making of a Planet - National Geographic Channel - YouTube
The atmophere we have today is not the atmophere we had 4.57 billion years ago.
In fact biological evolution gave us the oxygen atmophere we have today.
Scientific American
The Origin of Oxygen in Earth's Atmosphere
The breathable air we enjoy today originated from tiny organisms, although the details remain lost in geologic time.
"So how did Earth end up with an atmosphere made up of roughly 21 percent of the stuff?
The answer is tiny organisms known as cyanobacteria, or blue-green algae. These microbes conduct photosynthesis: using sunshine, water and carbon dioxide to produce carbohydrates and, yes, oxygen. In fact, all the plants on Earth incorporate symbiotic cyanobacteria (known as chloroplasts) to do their photosynthesis for them down to this day.
For some untold eons prior to the evolution of these cyanobacteria, during the Archean eon, more primitive microbes lived the real old-fashioned way: anaerobically. These ancient organisms—and their "extremophile" descendants today—thrived in the absence of oxygen, relying on sulfate for their energy needs.
The Origin of Oxygen in Earth's Atmosphere: Scientific American
Introduction to the Cyanobacteria
The Origin of Oxygen in Earth's Atmosphere: Scientific American
Architects of earth's atmosphere
Cyanobacteria are aquatic and photosynthetic, that is, they live in the water, and can manufacture their own food. Because they are bacteria, they are quite small and usually unicellular, though they often grow in colonies large enough to see. They have the distinction of being the oldest known fossils, more than 3.5 billion years old, in fact! It may surprise you then to know that the cyanobacteria are still around; they are one of the largest and most important groups of bacteria on earth.
Introduction to the Cyanobacteria
Introduction to the Cyanobacteria
Early 'see-sawing' Earth experienced hazy shades of life
" Earth's early atmosphere fluctuated between 'organic haze' and a 'haze-free' environment similar to that of Saturn's moon, Titan, a new study has revealed.
And this switch over 2.5 billion years ago was the result of intense microbial activity and would have had a profound effect on the climate of the Earth system.
Research, led by experts at Newcastle University, UK, revealed that the Earth's early atmosphere periodically flipped from a hydrocarbon-free state into a hydrocarbon-rich state."
Hazy shades of life on early Earth
Fossil raindrops reveal early atmosphere
Fossil raindrops reveal early atmosphere › News in Science (ABC Science)
Can you breath Methane, or primarily natural gas?
Fossil raindrops reveal early atmosphere › News in Science (ABC Science)
Your breathing Oxygen right now because the bacteria called cynobacteria evolved photosynthesis and changed the earth atmophere. Our atmophere today is a direct result of evolution. Look it up.