We are actually closest to the sun on about the 3rd of January (called ‘perihelion’) and furthest from it 6 months later (called ‘aphelion’.) The difference amounts to about 3% of our orbital diameter, so in January we are
Just for info. the fact that all planets (and moons etc.) move in ellipses was Kepler’s 1st law (his other two are equally amazing feats of observational astronomy completed without the use of a telescope!) If you are interested see here.