Earth and Major Evolutionary Changes

According to contemporary astronomers, what is the chronological evolution of the universe from its moment of inception at the Big Bang to the formation of the Earth? The earth started off really hot and it was all compressed together. When the universe began to cool down and get bigger the elements were formed. Than hydrogen and helium formed our stars and galaxies than when the milky-way galaxy took place that is when earth and the rest of our solar system was formed. According to researchers the earth and other planets all formed at the same time. 2. What is the evolution of Earth’s atmosphere? In particular, what has happened to the oxygen levels over the Earth’s 4.6 billion year history? Earth is the only planet that can support human and animal life. The sun is what helped formed all of the planets, but made earth different than all of the other planets. Repeated collisions called planetesimals created Earth. Meteorites impacted Earths surface. That is what happened to the oxygen levels over the billion years on earth’s history. 3. Why do you suppose that life began in the oceans rather than on land? What major evolutionary changes occurred during the 3 billion years between life’s inception and when it adapted to existence on land? I suppose life began in the ocean because there is a lot of space and room to grow. They started as a single cell living organism then into a certain form and than evolved into a land creature. For example a frog started out as an egg than turned into a tadpole and than turned into the land creature of a frog over the last 3 billion years a lot of evolutionary changes has occurred. From dinosaurs to the meteor shower to now caveman evolved and became more