Earth Science

Earth and the Sun formed 4.6 billion years ago from a collapsing cloud of dust and gas. This process began long after the Big Bang, the event 14 billion years ago that created all matter and energy. During the Big Bang, the universe existed as an unimaginably hot, dense bubble smaller than a pinhead. As it expanded and cooled, stars, galaxies, and planetary systems emerged. Earth grew as gravity pulled particles into larger clumps, eventually forming a molten world with unstable bedrock, intense geochemistry, and early geohazards.

Earth’s surface later transformed through plate tectonics, the central framework of modern geophysics and geotechnical science. The idea, rooted in early continental-drift observations, explains how vast plates shape mountains, oceans, and marine basins. The 50th anniversary of plate-tectonic theory was celebrated in 2017, marking its role as geology’s unifying model. Evidence from minerals, fossils, and groundwater systems shows that continents once formed the supercontinent Pangea about 240 million years ago, which began breaking apart 200 million years ago. Earlier and future supercontinents belong to Earth’s long Quaternary and pre-Quaternary cycles.

Despite their differences, Earth can be seen as a “less volatile” version of the Sun, because once lighter gases are removed, the relative proportions of heavy, refractory elements in both bodies are strikingly similar.