The Astronomical Time Scale (ATS) is an important emerging
alternative to radioisotope-based geochronology for the past 250
Ma. Quasi-periodic oscillations in the Earth’s orbit and axial
tilt have been a major driving factor in past climate
variations, and have left their record in the climate-sensitive
sedimentary record. Extended sequences of these sedimentary
oscillations have been calibrated to high-precision astronomical
models that have been calculated back in time in years from 1
January 2000 for hundreds of millions of years. These calibrated
cyclic sequences constitute the ATS. The ATS has a resolving
power that is directly related to the accuracy of the
astronomical modeling, and slowly declines from an impressive
0.02-0.04 myr (precession to obliquity scale) in the Neogene, to
0.1 myr (short orbital eccentricity scale) in the Paleogene, to
0.4 myr (long orbital eccentricity scale) in the Mesozoic. This
resolving power offers orders of magnitude improvement over that
of the current Geologic Time Sca