Astronomy Chapter 8 - 8.4
In terms of numbers, the most common life-forms on Earth are
microscopic creatures, too small to see with our eyes
According to the fossil record, how old is the oldest evidence of life forms on the surface of the Earth?
about 3.5 billion years
Which of the following is a way we believe that the early atmosphere of the Earth differed from the atmosphere we have today?
all of the above
The average temperature on planet Earth is higher than you would expect just from the heating of sunlight alone. What is the explanation for this?
carbon dioxide (and other gases) in the atmosphere cause a greenhouse effect