What?? The Earth DOES NOT Orbit the Sun??
I learned something new about our solar system. I always thought the Earth orbited the Sun, the center of the Sun. Right?
That is actually not true. The Earth, and all the other planets in our system, orbit THE CENTER OF MASS OF THE SOLAR SYSTEM. Here's the tricky part. Sometimes the center of mass of the solar system IS the exact center of the Sun but only for a moment every once in a while because the center of mass of the solar system is always changing. For example, right now, the center of mass of the solar system is outside the surface of the Sun. What?????
According to Ross Pomeroy in his article "Technically, Earth Does Not Orbit the Sun," he explains it this way: "The solar system is basically a massive game of tug of war, and all of the yanking balances out at a specific point: the center of mass, or "barycenter." Everything in the solar system orbits around that point. Sometimes, it's almost smack dab at the Sun's center. Right now, the barycenter is just outside the Sun's surface. But it's constantly changing depending upon where the planets are in their orbital paths."
You should read Ross's very interesting article here.. http://www.realclearscience.com/blog/2014/08/technically_the_earth_does_not_orbit_the_sun.html