The Earth's axis is tilted because of the gravitational influence of the Sun and the Moon on the Earth's equatorial bulge. The Earth's equatorial bulge is created by the centrifugal force caused by the Earth's rotation. The Sun and the Moon exert a gravitational force on this bulge, which causes the Earth's axis to precess, or wobble, over time. This wobble is what gives rise to the Earth's seasons.

The Earth's axis is currently tilted at an angle of approximately 23.4 degrees. This tilt is responsible for the Earth's seasons. As the Earth orbits the Sun, different parts of the Earth are tilted towards or away from the Sun. When a part of the Earth is tilted towards the Sun, it receives more direct sunlight and experiences summer. When a part of the Earth is tilted away from the Sun, it receives less direct sunlight and experiences winter.

The Earth's tilt also has an impact on the length of day and night. During the summer months, the days are longer and the nights are shorter. This is because the part of the Earth that is tilted towards the Sun is illuminated for a longer period of time. During the winter months, the days are shorter and the nights are longer. This is because the part of the Earth that is tilted away from the Sun is illuminated for a shorter period of time.