The Earth's orbit around the sun is slightly elliptical, not perfectly circular. This means that there's a point where the Earth is closest to the sun (perihelion) and a point where it's furthest away (aphelion).

Earth reaches perihelion around January 3rd, making it closer to the sun during that time. Aphelion happens around July 4th, when the Earth is farthest from the sun.

However, it's important to remember that this difference in distance doesn't cause the seasons. Seasons are caused by the tilt of the Earth's axis.