Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 beta 4/10/84; site seismo.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxl!houxm!houxz!vax135!floyd!cmcl2!seismo!flinn From: flinn@seismo.UUCP (E. A. Flinn) Newsgroups: net.physics Subject: Re: Reversing of Magnetic Poles Message-ID: <1458@seismo.UUCP> Date: Sun, 3-Jun-84 09:40:38 EDT Article-I.D.: seismo.1458 Posted: Sun Jun 3 09:40:38 1984 Date-Received: Tue, 5-Jun-84 19:30:44 EDT Distribution: net Organization: Center for Seismic Studies, Arlington, VA Lines: 30 |>>I have heard rumor that in the year 2000 (+ or - a few years) |>>the magnetic poles of the earth are going to do a flip-flop. |>>Is this only a rumor or is there some truth to it? No and yes. The strength of the geomagnetic field has been decreasing almost linearly for many years. The measurements made by Magsat in 1979 confirmed that *if* this linear decrease continues, the field strength will vanish in about 1100 years from now. Other changes are also taking place - the non-dipole components of the field are changing, there is the well-known westward drift of the geomagnetic field, and the inclination of the dipole component is gradually changing. |>>If it is true, is it going to be a gradual change of polarity or rapid? Gradual, if the linear trend continues. The field has reversed direction many times in geological history, so presumable the field will keep on changing, the north and south poles having changed identity. |>>What impact might it have on our magnetic shielding from |>>solar radiation? There is no evidence for species extinctions at the previous times of magnetic reversals, so it seems unlikely that life on earth would be profoundly affected. We will be bombarded by the solar wind for a few hundred years, and I haven't seen any discussions of the environmental implications of this sort of thing. -- Ted Flinn