According to the Davis-Greenstein mechanism, the grains spin rapidly with their rotation axis along the magnetic field. Source: Internet
After a short interval, the top settles into a motion in which each point on its rotation axis follows a circular path. Source: Internet
A Mercator map can therefore never fully show the polar areas (as long as the projection is based on a cylinder centered on the Earth’s rotation axis; see the Transverse Mercator projection for another application). Source: Internet
Besides the equator, four other parallels are of significance: :: The plane of the Earth's orbit about the sun is called the ecliptic and the plane perpendicular to the rotation axis of the Earth is the equatorial plane. Source: Internet
Axial tilt and seasons main Earth's axial tilt (or obliquity ) and its relation to the rotation axis and plane of orbit The axial tilt of the Earth is approximately 23.439281°. Source: Internet
In the non-trivial case (H is not the identity) this means that φ(H) is conjugation of operations by the reflection (a rotation axis and the direction of rotation are replaced by their "mirror image"). Source: Internet