Last Sky and Tel or Science News (IIRC) had article on earth's magnetic field being the 'weird thing to explain' as opposed to Venus lack of a magnetic field.
The argument being the no (or really weak) magnetic field is the 'default' characteristic of inner rocky planets and earth's relatively stronger field being what needs explained. And the explanation is the giant early impact that formed our moon in an oblique impact as being sufficient to disrupt a planetary magnetic field via deep mixing of the early earth's inner layers. The resulting core/mantle being much more favorable to allowing a stronger field to develop and persist.
So what's the angle on ET ??
We've taken earth to be a 'typical' rocky planet. Well, it's now less 'typical' than it was with this better understanding of Venus. The stronger field is a good thing for allowing evolution at a more controlled rate and regulating irradiation effects here. But we otta consider it another rather more rare characteristic of Minshara class worlds which we might want to be more common in the galaxy than they might actually be.
The argument being the no (or really weak) magnetic field is the 'default' characteristic of inner rocky planets and earth's relatively stronger field being what needs explained. And the explanation is the giant early impact that formed our moon in an oblique impact as being sufficient to disrupt a planetary magnetic field via deep mixing of the early earth's inner layers. The resulting core/mantle being much more favorable to allowing a stronger field to develop and persist.
So what's the angle on ET ??
We've taken earth to be a 'typical' rocky planet. Well, it's now less 'typical' than it was with this better understanding of Venus. The stronger field is a good thing for allowing evolution at a more controlled rate and regulating irradiation effects here. But we otta consider it another rather more rare characteristic of Minshara class worlds which we might want to be more common in the galaxy than they might actually be.
The granting of a pardon is an imputation of guilt, and the acceptance a confession of it.
