The Earth and all other planets in the Solar System orbit the Sun in slightly elliptical orbits and therefore the distance of each planet varies somewhat. Venus is the planet with the most circular orbit and Mercury the most eccentric. Orbital eccentricity is the parameter that describes the amount by which an orbit around another body deviates from a perfect circle. For Venus the value is 0.0068 which is close to a perfect circle. Mercury has a much more eccentric orbit at 0.2056 while the Earth has a value of 0.0167.

For our planet this means that the distance from the Sun varies between 0.9832899 AU at perihelion (closest) to 1.0167103 AU at aphelion (most distant). This corresponds to minimum and maximum distances of 147,098,074 kilometres (91,402,330 miles) and 152,097,701 kilometres (94,508,948 miles) respectively. However, the story is not so simple. Due to gravitational perturbations of the Moon and to a lesser extent the planets, the Earth's distance at perihelion and aphelion is not fixed and varies by up to 30,000 kilometres or 18,640 miles. The date of perihelion occurs between January 2nd and 5th. In 2016, the Earth reaches perihelion on January 2nd at a distance of 0.9833039 AU (147,100,170 kilometres or 91,403,632 million miles). This is slightly more than the mean value.

The diagram below shows the orbit of the Earth. Note that the elliptical form is strongly exaggerated for display purposes.