Imprint of Galactic dynamics on Earth's climate



A connection between climate and the Solar system's motion perpendicular to the Galactic plane during the last 200 Myr years is studied. An imprint of galactic dynamics is found in a long-term record of the Earth's climate that is consistent with variations in the Solar system oscillation around the Galactic midplane. From small modulations in the oscillation frequency of Earth's climate the following features of the Galaxy along the Solar circle can be determined: 1) the mass distribution, 2) the timing of two spiral arm crossings (31 Myr and 142 Myr) 3) Spiral arm/interarm density ratio (ρarm/ρinterarm ≈ 1.5–1.8), and finally, using current knowledge of spiral arm positions, a pattern speed of ΩP = 13.6 ± 1.4 km s–1 kpc–1 is determined. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)