For several billion years after the “Big Bang”, the earth was still just a cloud of dust. What it was to become was uncertain until between 4.5 and 3.8 billion years ago when the dust settled into a solid globe. The earth became so violent that it was not clear whether the shape would last or not. It exploded loudly with fire and rock. They were in time to produce carbon dioxide, nitrogen, water vapour and other gases, which were to make the earth’s atmosphere. What is even more important is that as the earth cooled down, water began to appear on its surface.

No one knows exactly how the earth began, as it happened so long ago. However, according to a widely accepted theory, the universe began with a “Big Bang” that threw matter in all directions. After that, atoms began to form and combine to create stars and other bodies.

First Stop (Para. 1-2)

一个被广泛接受的理论

= in every direction朝四面八方

一团

冷却