Make the summary from this article We believe the Earth is about 4.6 billion years old. At percent, we are forced to look to otherbodies in the solar system for hints as to what the early history of the Earth was like. Studies

of our moon, Mercury, Mars, and the large satellites of Jupiter and Saturn have provided

ample evidence that all these large celestial bodies had formed. This same bombardment

must have affected Earth as well. The lunar record indicates that the rate of impacts

decreased to its present low level about 4 billion years ago. On Earth, subsequent erosion

and crustal motions have obliterated the craters that must have formed during this epoch.

Scientists estimate the Earth’s age by measuring the ratios of various radioactive elements

in rocks. The oldest Earth’s rocks tested thus far are about 3 1/3 billion years old. But no

one knows whether these are oldest rocks on Earth. Tests on rocks from the moon and on

meteorites show that these are about 4.6 billion years old. Scientists believe that this is the

true age of the solar system and probably the true age of the Earth​