Earth's orbit is slightly elliptical, so the distance from the sun varies over the year. At its closest approach(perihelion), the distance is about 3% less than its furthest(aphelion). In our current orbit, perihelion occurs around 3 Jan, when Earth receives about 6% more solar radiation than it does at aphelion, around 4 July. When it is most elliptical, Earth receives 20%-30% more solar radiation at perihelion than aphelion. The current orbit is close to the lower range of eccentricity.