What is the slant of the earth called?

The Earth's tilt is 23.5 degrees on its axis. However the earth's tilt varies over a 42,000 year period,  ranging from 22.1 degrees to 24.5 degrees.The direction that the Earth's axis is pointed  also changes over a long cycle, lasting almost 26,000 years. Right now, the Earth's north pole is pointed towards the star Polaris. Over the course of this cycle, the seasons for summer and winter reverse (at 13,000 years), and then return to their original positions (after another 13,000 years).All the planets in the solar system have some amount of axial tilt. Mars is very similar to the Earth at 25.2 degrees, while Uranus is tilted right over at 97.8 degrees.

They became more resistant.