People find all kinds of things when they dig into the ground. Scientists, for example, are discovering the history of the solar system — how the orbits of Earth and the other planets have changed over the last couple of hundred million years.

Astronomers can project the motions of the planets millions of years into both past and future. Beyond a certain range, though, their forecasts break down. That’s because the orbits of the planets are chaotic. The gravity of every planet and asteroid pulls at everything else. Over time, that causes changes in their orbits.

Earth’s orbit changes, too. And one way to map those changes is to dig deep into the rocks. They show changes in the climate, magnetic field, and other factors. Comparing rocks from several locations, but from the same time period, helps scientists piece together what was happening in the solar system.

They took deep samples of rocks in New Jersey in the 1990s. They added more, from Arizona’s Petrified Forest, a few years ago. Now, they’re digging up more from the U.K., and planning digs in the Four Corners region and elsewhere. They’re probing rock layers that are about 200 million years old. Those layers were deposited at the end of the Triassic period and the start of the Jurassic — the time of the rise of the dinosaurs.

Those rocks will reveal details about Earth’s climate, its life — and its orbit: studying the solar system far below Earth’s surface.

Script by Damond Benningfield