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A Correlated History of the Universe $25 ADD TO CART

A Galactic Orbit Model for Periodic Mass Extinction

New Theory Explains Timing of Major Impacts and Extinction Events

Life on planet Earth has experienced 6 major and several minor extinction events over the past 620 million years. Statistical analyses suggest a periodic nature to these events. However, no model has been able to elegantly explain the apparent non-randomness in the data. A new astronomical model presented here, the Galactic Orbit model, shows a much stronger correlation with extinction and impact data (both craters and extraterrestrial geochemical signatures in Earth sediments) than previous models. It explains periodicity by invoking a 186 million-year galactic orbital period (corresponding to a galactic "year" for our solar system) with three discreet zones of high extinction for every trip around the galactic nucleus.

In recent years, two periodic extinction models have received the most attention in the scientific community and the media. The first is known as the Nemesis model and the second is the Galactic Plane transit model. Both involve a perturbation of Oort cloud comets, resulting in comet showers to the inner solar system. One or more of these comets then strike the Earth, causing catastrophic environmental changes and mass extinction of species.

The Nemesis model asserts that a somewhat massive solar companion gravitationally disrupts the Oort cloud at perihelion every 26 million years. However, such an object has not been found in spite of searches. Furthermore, an object with the necessary mass and orbital period is likely to have an unstable orbit. Passing stars would probably have stripped it away from our sun eons ago. The Galactic Plane transit model asserts that our solar system’s passage through the matter-rich galactic plane every 32 million years provides sufficient gravitational flux to disrupt Oort cloud comets. This idea is similar to "disk stripping" of globular clusters’ outer stars, also thought to occur due to passage through the galactic plane.Both of these models fail the predictions test. A group of extinctions should line up on 26 or 32 million year intervals. No such grouping is observed in the fossil record, although gaps of 26-32 million years are sometimes observed between extinctions.

The periodic nature of impacts and extinctions is displayed in detail on my educational map entitled:"A Correlated History of the Universe" by Pan Terra Inc. Notice the four largest probable impact events:(the K/T, P/Tr, O/S, Stu/V boundaries) are evenly spaced by ~186 million year intervals. The Galactic Orbit model implies that these four events occurred when our solar system passed through the most dangerous zone, or Zone-1. The impact/extinction data also suggests 2 minor Zones, also causing extinctions with a 186 million year period (just like Zone-1). Zone-2 transit follows Zone-1 transit by about 32 million years. Zone-3 follows Zone-2 by about 40 million years. After we get past Zone-3, there is a relatively quiet gap of 114 million years until the solar system returns to Zone-1.

An analogue to this model would be the annual meteor showers seen from Earth. The comet debris trails that cause the showers are basically fixed with respect to earth's orbit. We hit them the same time every year like clockwork as we orbit the sun. On the galactic scale, the time required for our solar system to make a lap around the galactic nucleus has been estimated to be in the range of 200-250 million years. The Galactic Orbit model suggests that 186 million years might be the effective period for our solar system. Perhaps we encounter stationary zones or features (relative to our galactic orbit) where gravitational flux or possibly shockwaves cause Oort cloud comets to venture into the inner solar system in large numbers.

Some candidate agents include spiral arms, giant molecular clouds, interactions between our galaxy and others, rapid bursts of star formation, supernovae generating shockwaves, etc. There may be multiple causative agents in this model. The 186 million year period and the three dangerous zones are the key ideas.The Galactic Orbit model might explain why the 26-32 million year periodicity ideas became popular. What researchers may actually have been detecting with statistical analyses are the stagger times (or sums and multiples thereof) between the three galactic danger zones.

Some predictions of the Galactic Orbit model can be tested. We should see a repeating pattern of Zone-1, 32 million year gap, Zone-2, 40 million year gap, Zone-3, 114 million year gap, then back to Zone-1. Research indicates a strong correlation between the predictions, the impact data and the extinction record. Also successfully predicted are the big gaps without mass extinction, which the other theories can’t explain. Curiously, the Earth’s magnetic field seems to stabilize for extended periods during this long 114 million year quiescent gap, as suggested by the Kiaman superchron preceeding the P/Tr and the Cretaceous magnetic quiet zone preceeding the K/T.

The impact and extinction data for Earth is a complex natural history puzzle. The Galactic Orbit model succeeds in predicting all of the major impact/extinction events as well as the long, relatively quiet times in between. One additional prediction is for an extraterrestrial signature to be found in rocks deposited during the Silurian/Devonian boundary interval. All of the other predicted times have strong statistical correlation with mass extinction, craters, and/or extraterrestrial geochemical signatures of various types. Events like the Jurassic/Cretaceous boundary (where craters and moderate extinction are present but the timing does not fit with the predictions of the model) would be caused by other culprits including random comets, random large asteroids, random gravitational effects from passing massive bodies or shockwaves/radiation from proximal exploding bodies(supernovae).

The question arises, where are we are now? Our solar system will hit the Zone-3 peak in about 7 million years. Given the cosmic scales and dating uncertainties, one might say our foot is at the door of Zone-3. In terms of galactic geography, we are beginning to enter the inner part of the Orion spiral arm. The last time we were "here", an 80km diameter crater (Puchezh-Katunki in Russia) greeted Earth and some of the dinosaur groups of that time had a noticeably bad year. On the Zone-3 visit previous to that (186 million years earlier), multiple craters and late Devonian mass extinctions were the result, perhaps the fourth or fifth worst extinction known from the fossil record. The Galactic Orbit model predicts 365 million years ago for the danger peak. We actually have evidence for two discreet extinction events during this interval, the Frasnian/Fammenian at ~367mya and the Devonian/Carboniferous at ~360mya. The good news is that the ultimate killer, Zone-1, is still 120 million years away and may be correlated to our solar system passing through the Crux spiral arm of the Milky Way.

If this model or something like it is shown to be useful, it might lead astronomers to examine our solar system’s local neighborhood in more detail, along with a closer look at the long-period comet data. It might be possible to determine favored directions from which comets might be emanating and focus more observational assets toward those regions.

In the course of my research, I occasionally discover something that merits additional publishing efforts to properly disseminate the discovery through the scientific community. I am seeking collaboration with interested parties who publish in the area of galactic dynamics, with the goal of refining and publishing the Galactic Orbit model in an appropriate, peer-reviewed publication.

For additional information contact: Paul R. Janke, President, Pan Terra Inc

email curator@pconline.com