Earth's orbital history: Comparisons

COMPARISON of Earth's orbital eccentricity in different simulations (right) near the Oligocene-Miocene boundary (23.9 Ma) shows large differences. Isotope data (Zachos et al., 1997; Shackleton et al.,1999) will be compared to our results to provide better astronomical calibration of the geological time scale. Eventually, the geological record and orbital computations need to be reconciled.

Note the large difference between our results and those of Laskar (1990).

The difference between R7 and R9 for this time period is too small to be noticeable. After about 70 Ma, however, the two simulations diverge.

WHILE R7 and R9 are almost identical between 60 and 70 MA, they are visibly different only 10 Ma later. We plot on the right low-pass filtered eccentricity since this is the type of signal one can recover from geological records.

MORE:

Chaotic transitions

Background image:
NASA/JPL/Malin Space Science Systems

(F. Varadi)