Scientists estimate that the Earth is about 4.54 billion years old. This estimate is based on several lines of evidence, including:

* Radiometric dating: This technique measures the decay of radioactive isotopes to determine the age of rocks and minerals. The oldest rocks on Earth have been dated to about 4.4 billion years old.

* Meteorites: Meteorites are pieces of rock and metal that have fallen to Earth from space. Some meteorites contain minerals that have been dated to over 4.5 billion years old. This suggests that the material in these meteorites formed before the Earth itself.

* Cosmogenic nuclides: These are isotopes that are produced by the interaction of cosmic rays with atoms in the Earth's atmosphere. The amount of cosmogenic nuclides in rocks can be used to date the rocks' exposure to the atmosphere, and thus to estimate the Earth's age.

Did Scientists Figure It Out?

Yes, scientists have figured out how old the Earth is. The evidence for the Earth's age is strong and consistent, and there is no reason to believe that this estimate will change significantly in the future.