The average distance at which Earth orbits the sun is 92,955,807 miles.
However, this number is variable, as the Earth revolves around the sun in a slightly elliptical orbit. This means that at perihelion (the point where Earth is closest to the sun, which always happens in January) the center of the Earth is only about 91.4 million miles from the center of the sun. Since the orbit is elliptical, there is conversely a point at which the center of the Earth is furthest from the center of the sun – the aphelion. Aphelion occurs every year in July when our planet’s center is about 94.5 million miles from the sun’s center. As you can see, this is only a difference of about 3.1 million miles. Though the difference seems substantial, it only equates to 3%. In fact, to the human eye, this 3% difference is virtually imperceptible when comparing this orbital ellipse to an ordinary circle.
How Does Our Distance From the Sun Affect the Earth?
Some people, when they learn that our distance from the sun is variable, think that this is the cause of the seasons. This conclusion seems logical, but it is mistaken. The change in distance is so minute that it has very little actual effect on climate. It does have some effect – however this is negligible. We are slightly cooler at perihelion and slightly warmer at aphelion. The real reason for the seasons is, in fact, the result of the tilt of the axis of the planet. This tilt can be understood by imagining that a straight line runs from the South Pole to the North Pole, through the center of the Earth. This imaginary line through the poles is not vertically straight up and down, but at a diagonal of roughly 23 degrees. This is the tilt of our planet, and this imaginary tilted line is what the Earth spins around at a rate of one spin every 24 hours. In turn, this rate of spin is why one whole day lasts exactly 24 hours. If you look at any quality globe, you will see that it is tilted just like it is in reality, as viewed on an axis from space.
How Far Is Earth from the Sun?” Space.com. N.p., n.d. Web. 16 Jan. 2013. <http://www.space.com/17081-how-far-is-earth-from-the-sun.html>.
Earth at Perihelion.” – NASA Science. N.p., n.d. Web. 16 Jan. 2013. <http://science.nasa.gov/science-news/science-at-nasa/2001/ast04jan_1/>.