[meteorite-list] No Nemesis No periodicity

From: Richard Kowalski <damoclid_at_meteoritecentral.com>
Date: Tue, 2 Aug 2011 15:12:55 -0700 (PDT)
Message-ID: <1312323175.48143.YahooMailNeo_at_web113614.mail.gq1.yahoo.com>

As has been discussed on this list before, this "theory" died well over a decade ago, both because it is pretty much impossible for Nemesis to exist, despite some wild machinations by some to try to keep the idea going.

The idea of periodicity disappears if anyone spends more than 5 minutes investigating it for themselves. In the last 600 million years there have been 18 Mass and minor extinction events. Many of these took about 15 million years to occur from start to finish but a few took only 1 million or less or took as long as 42 million years from start to finish.

The average period between all of these events is 30.6 million years, but the average is not typical. Some occurred in about a million years after the previous one, but other extinction events happened as much as 80 million years apart.

There is no Nemesis
There is no periodicity in the timing of extinction events.
We've been studying the surface of Mars by spacecraft for nearly 50 years and had the first orbiters were in place 35 years ago and we have a pretty good handle on impact rates, despite the single note continuously played by a small group of tooters.

--
Richard Kowalski
Full Moon Photography
IMCA #1081

Received on Tue 02 Aug 2011 06:12:55 PM PDT