Perihelion is the point where the Earth is closest to the Sun (91.4 million miles, or 147 million kilometers). This occurs around January 3 every year. Aphelion is when our planet reaches its farthest point from the Sun (94.5 million miles, or 152 million kilometers) around July 4. This variation does not have much effect on weather patterns or seasons.
This old chart explains how Earth’s orbit tilt results in the seasons, as well as how eclipses are formed, the phases of the Moon, and the latitudinal zones.