Why is the earth tilted?

Because the globe is made by imitating the movement of the earth, there is an intersection angle between the equatorial plane of the earth and the common rotation plane of the earth around the sun-the intersection angle of yellow and red. The intersection angle between yellow and red is 23.5 degrees, so the angle between the earth axis and the earth's orbital plane is always 66.5 degrees. So it is tilted when it is made into a globe.

Extended data:

The axial inclination angle can also be equivalently expressed as the angle between the plane of planetary orbit and the plane perpendicular to the rotation axis. In the solar system, the earth's orbital plane is the ecliptic, so the inclination of the earth's axis is specially called the ecliptic angle, which is expressed by ε (ε of Greek letters).

At present, the axial inclination of the earth is about 23.44 (23 26'). Although the inclination of the axis is in the same direction all year round, because the earth revolves around the sun, the hemisphere originally facing the sun will gradually become the hemisphere facing away from the sun, and vice versa.

This effect is the main reason of seasonal variation (the influence of reference sunshine angle on climate). No matter which hemisphere is facing the sun, the daily sunshine time in that hemisphere will be longer. The closer the angle of sunlight touching the ground at noon is to the vertical direction, the more energy the area will get in unit area.