Final answer:
The modern Earth is different from the Earth over 4 billion years ago in terms of the atmosphere, radiation levels, and geologic activity.
Step-by-step explanation:
The modern Earth is different from the Earth over 4 billion years ago in several ways. Firstly, the atmosphere of early Earth was very different from today's atmosphere, likely consisting of gases like methane, ammonia, and water vapor. Over time, the atmosphere evolved to its current composition, primarily made up of nitrogen, oxygen, and trace amounts of other gases. Secondly, early Earth experienced extreme radiation due to the higher activity of the Sun, while the radiation levels are much lower now. Lastly, there was significant geologic upheaval and volcanic activity on early Earth that shaped its surface, but these activities have decreased significantly in the present day.