Lunar and planetary perspectives on the geological history of the Earth

During the latter part of the last century, a profound change took place in our perception of the Earth. First, this change was holistic: Plate tecton ic theory provided a unifying theme that seems to explain disparate observa tions about the Earth and how it works, and lets us see the Earth as a plan et. Secondly, actually seeing the Earth from the Moon, and exploring the ot her planets provided additional perspectives on our own home planet and has tened the decline of scientific terracentrism. Thirdly, learning that the u niqueness of the Moon in terms of size and aspects of its chemistry may be due to its derivation from the Earth as the result of a giant impact, provi ded a concrete filial link. Finally, the geological record revealed by expl oration of the Moon and planets has provided us with the missing chapters i n the dynamic history of the Earth. We now know that gargantuan impact basi ns formed in Earth's formative years and that impact events are likely to b e the cause of many punctuations in Earth's biological evolution. Perspecti ves on ancient tectonic activity are provided by Mercury, Venus, Mars, and the Moon, and show that the Earth has changed considerably since its youth. Widely varying volcanic eruption styles are seen on the planets, providing insight into how puzzling rocks from early Earth history formed. The compo sition of planetary atmospheres has revealed the unusual nature of Earth's, and its link to the evolution of life. The atmospheres of the planets have undergone radical changes with time, providing clues to Earth's history an d destiny. Fundamentally different hydrological cycles on Earth, Venus, Eur opa and Mars, and evidence for significant changes with time, have provided insight into Earth's history. The probable presence of oceans on Europa an d Mars has changed our thinking about the origin and evolution of life on E arth. We no longer think of the Earth in isolation. Instead, Earth is now p erceived of as a member of a family of planets, each of which provides impo rtant missing information and perspective on the other, and together reveal the fabric of the history of the Solar System. Future exploration and pers pectives will place our Solar System in the context of all of the others.