Is the earth’s axis always in the same plane? Does the tilt stay the same? What does this effect?

Oct 28, 2016

Explanation:

A line is an 1-D space. Plane is a 2-D space and the Earth is a 3-D

space. Two lines (in same or different directions ) determine a plane

Earth's axis is a $s t r a i g h t$ line parallel to the ( the little away ) polar

axis. So, relatively, both are coplanar..

Over a period of Great Year (nearly 25800 years), the polar axis

moves ( relative to the Earth ) along the surface of a cone of semi-

vertical angle ${23.4}^{o}$, keeping its direction relative to the normal

to the ecliptic as the same ${23.4}^{o}$. This is called precession

motion. The average variation ($\pm {0.00006}^{o}$/year, in the range

from ${22.04}^{o}$ through ${23.44}^{o}$ to ${24.50}^{o}$, over a period of

about 41 K years ) of this angle, about the mean 23.27^o. is nearly 0,

Of course, poles move but its precession and nutation ( nodding

across ) are incognizant.