Without a tilt in the earth's axis of rotation, there would be no what?
The tilt in the Earth's axis allows for the progression of seasons as the Earth revolves around the sun.
Because of the tilt, in the months of November, December, and January, the southern hemisphere receives more direct sunlight than does the northern hemisphere. This results in warmer temperatures - summer - in the southern hemisphere and colder temperatures - winter - in the northern hemisphere. As the Earth revolves around the sun, the positions are reversed in May, June, and July. The northern hemisphere receives the most direct sunlight and has summer, while the southern hemisphere experiences less sunlight, cooler temperatures, and the winter season.