Mötesplats Rydberg: Birger Schmitz - Extraterrestrial spinels and the astronomical perspective on Earth's geological record and evolution of life – What can 50 tons of rock and 100,000 litres of hydrochloric acid tell us?

Tuesday 3 Apr 2018, 15:15 → 16:15 Europe/Stockholm

Rydbergsalen (Fysiska institutionen-Physics Department)

We use relict, sand-sized spinel grains from decomposed extraterrestrial material in ancient sediments for the very first reconstructions of the variations in the types of meteorites that fell on Earth through the ages. Meteorite falls are rare and meteorites weather and decay rapidly on the sea floor making it a challenge to reconstruct ancient fluxes. The refractory spinels are recovered by dissolving tons of ancient sediments in acids. Recently we showed that the meteorites that fell on Earth about 500 Myr ago were very different from the meteorites that fall today, raising a major conundrum in our understanding of the solar system. Our spinel data from Earth's geological record can be related to the formation of major asteroid families in the asteroid belt, or minute, chaos-related, perturbations of the orbits of the planets. The timing of these events in the geological record can be compared with data from the recent Gaia space telescope mission about times when the solar system, in its 250 Myr orbit around the center of our galaxy, enters or leaves the spiral arms or passes close to other stars.