Earth Science Regents Practice Exam 2025 - Free Regents Practice Questions and Study Guide

The correct response indicates that the solar system, along with Earth, is approximately 4.6 billion years old. This estimation is based on several lines of evidence, including the age of the oldest meteorites found, as well as radiometric dating of the oldest rocks on Earth and the Moon. Chlorine isotope ratios and the presence of lead isotopes in these ancient materials suggest a consistent age across various samples, reinforcing the conclusion that the formation of the solar system and the planets, including Earth, occurred around 4.6 billion years ago.

Other options present ages that are not supported by scientific evidence. For example, 13.7 billion years refers to the estimated age of the universe itself, not just the solar system. Meanwhile, estimates like 3.5 billion years pertain to specific geological events or the ages of the oldest known rocks, which is significantly younger than the formation of the Earth or solar system. Similarly, the figure of 5 billion years is also not accurate according to current scientific understanding and evidence. Thus, the figure of 4.6 billion years best reflects the consensus among scientists regarding the age of both the solar system and Earth.