The sun's energy is able to reach Earth as it is electromagnetic, which allows it to move through space, and it travels in straight lines, which means it hits Earth. However, in order for the sun's radiation to successfully deliver energy on Earth, the Earth's axis must be at a certain tilt.
The sun is a star made from hydrogen that burns hot enough to fuse hydrogen nuclei together, which forms helium nuclei that release energy. The energy on the sun is known as solar radiation and, as it is electromagnetic, it has the properties needed to cut through space. This energy moves at 186,000 miles per second, allowing it to move fast enough to reach the Earth's surface. As radiation travels in straight lines, it moves from the sun equally in all directions.
The Earth is in the sun's path, so it stands in the way of and accepts its energy. How the sun's energy is used by the Earth depends on its axial tilt. At 23.5 degrees, the axial tilt allows the sun to cause four seasons. However, if it became slightly lower, there would be a summer and winter, but no spring or autumn. The Earth's axial tilt changes around once every 41,000 years.